Please Wait... While Loading Full Video

Previous Year Questions of Some Important Chemical Compounds

Previous Year Questions of Some Important Chemical Compounds

Q 2118534400

Which of the following substances are harmful for health if present in food items?
1. Pesticide residues
2. Lead
3. metanil yellow
4. Mercury

Select the correct answer using the codes given below
NDA Paper 2 2016
(A)

`1` and `2`

(B)

`1, 2` and `4`

(C)

`3` and `4`

(D)

`1, 2, 3` and `4`

Solution:

Pesticide residues lead to cancers and sterility in

humans. Lead is emitted from petroleum as

by product. If injected in us specially young one then

adversely affecting brain and nervous system. In

adults high blood pressure and kidney damage occur

due to lead. Metanil yellow, a principal

non-permitted food colour, leads neurotoxicity on the

developing and adult's brain. Mercury if injected in

body then adversely affect nervous, digestive and

immune system and other organs such as lungs and

kidney.
Correct Answer is `=>` (D) `1, 2, 3` and `4`
Q 2139501412

Which of the commonly used household item(s) release Bis phenol `A (BPA)` which is endocrine disrupt or and bad for human health?

1. Steel utensils
2. Plastic coffee mugs
3. Aluminium utensils
4. Water storage plastic bottles
Select the correct answer using the codes given below
NDA Paper 2 2016
(A)

Only `1`

(B)

`1` and `2`

(C)

`2` and `4`

(D)

`1 ,2` and `3`

Solution:

Bisphenol `A (BPA), (CH_(3))_(2) C(C_(6) H_(4) OH)_(2)` is employed

to make certain plastics and epoxy resins. It is used

for making plastic mugs, water storage plastic

bottles, beverage cans etc. Typically, phenol

containing molecules similar to `BPA` are known to

exert weak oestrogenic activities as thus it is also

considered as an Endocrine Disruptor `(ED)` and

oestrogenic chemical.
Correct Answer is `=>` (C) `2` and `4`
Q 2169701615

Which one of the following is the chemical name for baking soda?
NDA Paper 2 2016
(A)

Sodium bicarbonate (sodium hydrogen carbonate)

(B)

Sodium carbonate

(C)

Potassium bicarbonate (potassium hydrogen carbonate)

(D)

Potassium carbonate

Solution:

The chemical name of baking soda is sodium

bicarbonate sodium hydrogen carbonate, `(c)`

`NaHCO_(3)`. It is produced using sodium chloride as one

of the raw materials.
Correct Answer is `=>` (A) Sodium bicarbonate (sodium hydrogen carbonate)
Q 2189612517

The questions consist of two statements, `text(Statement I)` and `text(Statement II)`. You are to examine these two statements carefully and select the answer.

`text(Statements I)`. Petroleum is a mixture of many different hydrocarbons of different densities.
`text(Statements II)`. The grade of petroleum depends mainly on the relative proportion of the different hydrocarbons.

NDA Paper 2 2016
(A)

Both the Statements are individually true and Statement II is the correct explanation of Statement I.

(B)

Both the Statements are individually true but Statement II is not the correct explanation of Statement I.

(C)

Statement I is true but Statement II is false.

(D)

Statement I is false but Statement II is true.

Solution:

Petroleum is a mixture of a very large number of

different hydrocarbons; the most common are alkanes,

cycloalkanes, aromatic hydrocarbons etc.

The relative percentage of hydrocarbons varies and is

responsible for different grades of petroleum.
Correct Answer is `=>` (B) Both the Statements are individually true but Statement II is not the correct explanation of Statement I.
Q 2149323213

The phosphorus used in the manufacture of safety matches is.
NDA Paper 2 2016
(A)

red phosphorus

(B)

black phosphorus

(C)

white phosphorus

(D)

scarlet phosphorus

Solution:

Red phosphorus is used in the manufacture of safety matches. Red phosphorus exists as an amorphous network. Red phosphorus does not ignite in air at temperature below `240^(0)C`.
Correct Answer is `=>` (A) red phosphorus
Q 2189423317

One of the main causes of air pollution in cities is emissions from vehicles like cars and trucks. Cars emit various pollutants which are bad for human health when inhaled, like

1. nitrogen oxides `(NO _(x)) `
2. carbon monoxide `(CO)`
3. carbon dioxide `(CO_( 2) )`
4. benzene

Which of the above pollutants are not tolerated by human being even at very low level?
NDA Paper 2 2016
(A)

`1` and `4`

(B)

`1` and `2`

(C)

`1, 2` and `3`

(D)

`1, 2` and `4`

Solution:

`NO_(x)` (nitrogen oxides), `CO` (carbon monoxide),

benzene are main sources of air pollution. Nitrogen

oxides has a characteristic sharp, bitting odour. `CO` is

yet non-irritating gas and benzene has aromatic,

gasoline like odour which can't be tolerated even at

very low level can be lethal at higher concentration.
Correct Answer is `=>` (D) `1, 2` and `4`
Q 2129434311

Soap is the sodium or potassium salt of.
NDA Paper 2 2016
(A)

stearic acid

(B)

oleic acid

(C)

palmitic acid

(D)

All of these

Solution:

The mineral salts of higher fatty acids such as oleic

acid `(C_(17) H_(33) COOH)`, stearic acid `(C_(17) H_(35) COOH)`

and palmitic acid `(C_(15)H_(31)COOH)` etc. are called soaps.

Out of these, only sodium and potassium salts of fatty

acids being water soluble, are widely used for cleaning

purposes.
Correct Answer is `=>` (D) All of these
Q 2189634517

Match List `I` with List `II` and select the correct answer using the codes given below the lists.
NDA Paper 2 2016
(A)

`2 \ 3 \ 1 \ 4`

(B)

`2 \ 1 \ 3 \ 4`

(C)

`4 \ 1 \ 3 \ 2`

(D)

`4 \ 3 \ 1 \ 2`

Solution:

The mineral salts of higher fatty acids such as oleic

acid `(C_(17) H_(33) COOH)`, stearic acid `(C_(17) H_(35) COOH)`

and palmitic acid `(C_(15)H_(31)COOH)` etc. are called soaps.

Out of these, only sodium and potassium salts of fatty

acids being water soluble, are widely used for cleaning

purposes.
Correct Answer is `=>` (D) `4 \ 3 \ 1 \ 2`
Q 1618745600

Which one among the following is used in making gunpowder?
NDA Paper 2 2015
(A)

Magnesium sulphate

(B)

Potassium nitrate

(C)

Sodium stearate

(D)

Calcium sulphate

Solution:

Gunpowder is an intimate mixture of nitre i.e. potassium nitrate (6 parts), charcoal (1 part) and sulphur (1 part). Here potassium nitrate `(KNO_3)` behaves as a good oxidising agent and sulphur and charcoal burn vigorously in its molten state.
Correct Answer is `=>` (B) Potassium nitrate
Q 1658745604

The cleaning action of soap and detergent in water is due to the formation of
NDA Paper 2 2015
(A)

micelle

(B)

salt

(C)

base

(D)

acid

Solution:

Soap and detergent both have a water soluble polar end and fat soluble non-polar end. When applied to a dirty cloth, their non-polar parts surround the dirt (fat or oil) and the polar part remains towards water as shown below. The structure is called Micelle. When washed with plenty of water, it goes with water leaving behind a clean cloth.
Correct Answer is `=>` (A) micelle
Q 1618745609

The chemical used as a fixer/developer in photography is
NDA Paper 2 2015
(A)

sodium sulphate

(B)

sodium sulphide

(C)

sodium thiosulphate

(D)

sodium sulphite

Solution:

Sodium thiosulphate `(Na_ 2S_2O_ 2)` has the capacity to dissolve insoluble silver halides, so it is used in photography for fixing i.e. to remove unreacted silver bromide as shown below. `AgBr + 2Na_2 S_2O_ 3 -> Na_3 [Ag (S_2O_ 3)_ 2] +NaBr` Sodium argento thiosulphate
Correct Answer is `=>` (C) sodium thiosulphate
Q 1668256105

Washing Soda is the common name for
NDA Paper 2 2015
(A)

calcium carbonate

(B)

magnesium carbonate

(C)

sodium carbonate

(D)

Potassium carbonate

Solution:

Sodium carbonate decahydrate `(Na_2 CO_3 . 10 N_2O)`, because of its cleansing property is also known by the name washing soda.
Correct Answer is `=>` (C) sodium carbonate
Q 1638756602

Which of the following are the characteristics of organic farming?

1. Use of chemical fertilisers to improve soil
fertility.
2. Frequent decomposing and fallowing.
3. Use of herbs to control pests.
4. Higher productivity per hectare

Select the correct answer using the codes given below
NDA Paper 2 2015
(A)

1 and 4

(B)

1, 3 and 4

(C)

2 and 3

(D)

2, 3 and 4

Solution:

Organic farming is a method of farming which primarily aimed at cultivating the land and raising crops in such a way, as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (bio-fertilisers) to release nutrients to crops for increased sustainable production in an eco friendly pollution free environment. Some of these people are nomadic reindeer herders, living in the Tundra.
Correct Answer is `=>` (D) 2, 3 and 4
Q 1636756672

To weld metals together, high temperature is required. Such a high temperature is obtained by burning
NDA Paper 2 2015
(A)

acetylene in oxygen

(B)

LPG in oxygen

(C)

methane in oxygen

(D)

acetylene in nitrogen

Solution:

To weld metals together, high temperature is obtained by burning acetylene in oxygen.
Correct Answer is `=>` (A) acetylene in oxygen
Q 1666856775

Which one of the following gases is found in highest quantity in Exosphere?
NDA Paper 2 2015
(A)

Hydrogen

(B)

Helium

(C)

Nitrogen

(D)

Oxygen

Solution:

The exosphere the highest layer, is extremely thin and is where the atmosphere merges into outer space. It is mainly composed of very widely dispersed particles of hydrogen and some amount of helium.
Correct Answer is `=>` (A) Hydrogen
Q 1750423314

Turpentine oil in paints is used as a
NDA Paper 2 2014
(A)

pigment

(B)

film-forming material

(C)

thinner

(D)

drier

Solution:

Turpentine oil in paints is used as a thinner.
Correct Answer is `=>` (C) thinner
Q 1783312247

A fertiliser contains `20%` nitrogen by mass. To provide a fruit tree with an equivalent of `1 kg` of nitrogen, the quantity of fertiliser required is.
NDA Paper 2 2014
(A)

20 kg

(B)

0.20 kg

(C)

0.05 kg

(D)

5 kg

Solution:

Turpentine oil in paints is used as a thinner.
Correct Answer is `=>` (D) 5 kg
Q 1700734618

Which one of the following substances is most likely to be used as soap?
NDA Paper 2 2014
(A)

`CH_3 (CH_2 ) _(12) COOCH_3`

(B)

`CH_3 (CH_2 )_5O(CH_2 )_5 CH_3`

(C)

`CH_3 (CH_2 )_ (12) COONa`

(D)

`CH_3(CH_ 2)_(12) CHCl_2`

Solution:

`CH_3 (CH_2 )_ (12) COONa` is most likely to be used

as soap. A soap is the sodium salt (or potassium salt) of a

long chain carboxylic acid (or fatty acid).
Correct Answer is `=>` (C) `CH_3 (CH_2 )_ (12) COONa`
Q 2366080875

The following items consist of two statements, Statement I and Statement II. You are required to examine these two statements carefully.
Statement I Glass is not considered as a true compound.
Statement II Glass does not have a definite melting point.
NDA Paper 2 2013
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true, but Statement II is not t11e correct explanation of Statement It

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true

Solution:

Glass is an amorphous (non-crystalline) solid amorphous solids do not have a definite melting point or regular repeating units. An example of on amorphous solid is window glass.
Correct Answer is `=>` (A) Both the statements are true and Statement II is the correct explanation of Statement I
Q 2366080875

The following items consist of two
statements, Statement I and Statement II. You are
required to examine these two statements carefully.
Statement I Limestone decomposes when it is
heated in air.
Statement II Increase in the content of `CO_2` in
the atmosphere in recent years is mainly due to
the using of limestone in the manufacture of
cement.
NDA Paper 2 2013
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true, but Statement II is not t11e correct explanation of Statement It

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true

Solution:

When limestone is heated, it decomposes to give calcium oxide and carbon dioxide

`underset(Calcium Carbonate (Lime Stone))(CaCO_3) -> underset (Lime)CaO(s) + CO_2(g)`

Calcium oxide (or lime) is used on a large scale in the
manufacture of cement.
In the production of cement lime sediments ans smooth clay are
utilised as raw material. the lime sediments pro ride calcium oxide
(CaO).
Correct Answer is `=>` (B) Both the statements are true, but Statement II is not t11e correct explanation of Statement It
Q 2366080875

The following items consist of two
statements, Statement I and Statement II. You are
required to examine these two statements carefully.
Statement I Very little hydrogen is produced when sulphuric acid is added to calcium.
Statement II The salt that is produced, calcium sulphate, is insoluble.
NDA Paper 2 2013
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true, but Statement II is not t11e correct explanation of Statement It

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true

Solution:

Calcium reacts with dilute sulphuric acid to give calcium sulphat and hydrogen gas. lntial reactions is fast, but gradually slows down.This is because calcium sulphat is quite insoluble in water, which forms a protective layer on calcium and preventing the acid to react effectively with calcium.

`Ca(s) + H_2SO_4 (aq) -> CaSO_4 (s) + H_2(g)`
Correct Answer is `=>` (A) Both the statements are true and Statement II is the correct explanation of Statement I
Q 2366080875

The following items consist of two
statements, Statement I and Statement II. You are
required to examine these two statements carefully.
Statement I Zinc is used for galvanisation to protect iron from rusting.
Statement II Zinc is more reactive towards oxygen than iron.
NDA Paper 2 2013
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true, but Statement II is not t11e correct explanation of Statement It

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true

Solution:

Galvanisation is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting.
Correct Answer is `=>` (A) Both the statements are true and Statement II is the correct explanation of Statement I
Q 2306080878

Calcium Ammonium Nitrate (CAN) is a popular nitrogen fertilizer because it is.
NDA Paper 2 2013
(A)

slow supplier of nitrogen

(B)

having more percentage of nitrogen in it

(C)

fixing the nitrogen in the soil

(D)

capable of making the soil acidic

Solution:

Calcium Ammonium Nitrate (CAN), also known as nitro-limestone, is a popular nitrogen fertilizer because it is having more percentage of nitrogen in it. It is also used in place of ammonium nitrate where ammonium nitrate is banned.
Correct Answer is `=>` (B) having more percentage of nitrogen in it
Q 2336180972

Chromium oxide is used as an ingredient in paints to obtain
NDA Paper 2 2013
(A)

green colour

(B)

blue colourr

(C)

red colour

(D)

violet colour

Solution:

Chromium oxide as used as an ingredient is paints to obtain green colours.
Correct Answer is `=>` (A) green colour
Q 2386180977

Biogas consists of mainly
NDA Paper 2 2013
(A)

methane

(B)

ethane

(C)

butane

(D)

carbon dioxide

Solution:

Biogas typically refers to a gas produced by the breakdown of organic matter in the absence of oxygen. It comprises primarily rnethane (`CH_4` ) and carbon dioxide (`CO_2`) and may have small amounts of hydrogen sulphide (`H_2S`), moisture and siloxanes.
Correct Answer is `=>` (A) methane
Q 2316291170

Solutions of three enzymes were prepared namely lipase, trypsin and amylase, in order to remove stains frorn a piece of cloth. Out of these three enzyme solutions, only lipase could completely remove the stain. This indicates that the stain was due to
NDA Paper 2 2013
(A)

oil

(B)

protein

(C)

mixture of protein and oil soil

(D)

starch containing plant pigment

Solution:

The lipase is capable of removing fattey stains such as
fats, butter, salad oil, Sauces and the tough stains on collars and
cuffs.
Correct Answer is `=>` (A) oil
Q 2346291173

Match the following List I with List II and select the correct answer using the codes given below the lists.





Rock TypeComposition
(A) Sandstone (1) Rock formed from peat or other organic deposits
(B) Limestone(2) Clay, breaking easily into flat flake platests
(C) Coal (3)Calcium carbonate formed by precipitation
(D) Shale (4) Cemented sand grains

NDA Paper 2 2013
(A)

4, 1, 3, 2

(B)

2, 3, 1, 4

(C)

2, 1, 3, 4

(D)

4, 3, 1, 2

Solution:







Rock TypeComposition
Sandstone Clay, breaking easily into flat flake platests
LimestoneCalcium carbonate formed by precipitation
Coal Rock formed from peat or other organic deposits
Shale Cemented sand grains
Correct Answer is `=>` (B) 2, 3, 1, 4
Q 2347745683

Sodium stearate is a salt and is used
NDA Paper 2 2013
(A)

in gun powder

(B)

in paint

(C)

to make soap

(D)

to make fertilizer

Solution:

Sodium stearate is the sodium salt of stearic acid. Thus, white solid 's most common soap. It is found in many types of solid deodrants, rubbers, latex paints and inks. It is also a component of some food additives and food flavourings. It has the formula `C_18 H_35 NaO_2.`
Correct Answer is `=>` (C) to make soap
Q 2377745686

Which one among the following is the chemical formula of gypsum, which is an ingredient of cement?
NDA Paper 2 2013
(A)

`Ca_2SiO_2`

(B)

`CaSO_4 . 2 H_2O`

(C)

`CaO `

(D)

`CaSO_4 . 3 H_2O`

Solution:

Gypsum (also known as plaster of Paris) is a very soft sulphate mineral composed of calcium sulphate dihydrate, with the chemical formula `CaSO_4 . 2 H_2O` . Can be used as a fertilizer, is the main constituent in many forms of plaster and is widely mined.
Correct Answer is `=>` (B) `CaSO_4 . 2 H_2O`
Q 2387145987

Match the following






Column IColumn II
(A) Cellulose nitrate (1) Soft soap
(B) Potassium sulphate (2) Gun powder
(C) Potassium salt of fatty acids(3) Fertilizer
(D) Calcium oxide (4) Glass


NDA Paper 2 2012
(A)

2, 3, 1, 4

(B)

2, 1, 3, 4

(C)

4, 1, 3, 2

(D)

4, 3, 1, 2

Solution:

Cellulose Nitrate `->` Gun powder
Potassium sulphate `->` Fertilizers
Potassium salt of fatty acids `->` Soft soap
Calcium oxide `->` Glass
Correct Answer is `=>` (A) 2, 3, 1, 4
Q 2317356280

The most important raw materials used in the manufacture of cement are
NDA Paper 2 2012
(A)

potassium nitrate, charcoal and sulphur

(B)

limestone, clay and gypsum

(C)

transition metal oxides, sodium hydroxide or 'potassium hydroxide

(D)

limestone, sodium carbonate and silica

Solution:

In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The most important raw material used in the manufacture of cement are limestone, clay and gypsum. Cement used in construction js characterised as hydraulic or non-hydraulic. Hydraulic cements (e.g., Portland cement) harden because of hydration, chemical reactions that occur independently of the mixture's water content; they can harden even underwater or when constantly exposed to wet weather. The most important use of cement is the production of mortar and concrete.
Correct Answer is `=>` (B) limestone, clay and gypsum
Q 2377556486

Given below is an approximate composition of a substance

`CaO -> 60 -70% SiO_2 ->20 -25%`

`Al_2O_3 -> 5 - 10% Fe_2O_3 -> 2 - 3%`

The substance is

NDA Paper 2 2012
(A)

plaster of Paris

(B)

cement

(C)

marble stone

(D)

quartz

Solution:

Given approximate composition is cement.
Correct Answer is `=>` (B) cement
Q 2317056889

Which one among the following nitrogen compounds has the least percentage of nitrogen by mass?
NDA Paper 2 2012
(A)

`(NH_4)_3PO_4`

(B)

`NH_3`

(C)

`NH_4OH`

(D)

`NH_4NO_3`

Solution:

Percentage of nitrogen by mass
(a) `(NH_4 )3PO_4 -28.18%`
(b) `NH_3 - 82.25%`
(c) `NH_4OH - 39.96%`
(d) `NH_4NO_3 - 35%` (approx)
So, `(NH_4)_3PO_4` has the least percentage of nitrogen by mass.
Correct Answer is `=>` (A) `(NH_4)_3PO_4`
Q 2387156987

Which one among the following is the correct order of amount of lime (`CaO`), silica (`SiO_2` ) alumina (`Al_2O_3`) and ferric oxide (`Fe_2O_3`) in Portland cement?
NDA Paper 2 2012
(A)

`CaO > SiO_2 > Al_2O > Fe_2O_3`

(B)

`SiO_2 > CaO < Fe_2O_3 > Al_2O_3`

(C)

`Al_2O_3 > SiO_2 > CaO > Fe_2O_3`

(D)

`Fe_2O_3 > Al_2O_3 > SiO_2 < CaO`

Solution:

(a) There are four chief minerals present in a Portland cement grain tricalcium silicate `(Ca_3 SiO_5)` -50%, dicalcium silicate `(Ca_2SiO_ 4 )` -25%, tricalcium aluminate `(Ca_3Al_2O_5)`-12% and calcium alumino ferrite `(Ca_4Al_2 Fe_2 - nO_7 )`- 8%. The formula of each of these minerals can be broken down into the basic calcium, silicon, aluminium and iron oxides, i.e., `C = CaO, S = SiO_2, A = Al_2O_3, F = Fe_2O_3`
Correct Answer is `=>` (A) `CaO > SiO_2 > Al_2O > Fe_2O_3`
Q 2357567484

Which one among the following is the major constituent of sodalime glass'?
NDA Paper 2 2012
(A)

Sodium oxide

(B)

Calcium oxide

(C)

Calcium carbonate

(D)

Silica

Solution:

It is `Na_2O . CaO . 6SiO_ 2` .
Correct Answer is `=>` (D) Silica
Q 2327867781

The major component used in the preparation of different types of glasses is
NDA Paper 2 2011
(A)

silica

(B)

sodium borate

(C)

calcium silicate

(D)

sodium silicate

Solution:

Glass is a homogeneous mixture of silicates or
borosilicates of metals in silica. It is not a true solid. It is
essentially a solution of silica in a mixture of other silicates. The
major components used in the preparation of different types of
glasses is silica `(SiO_2)`. Silica is used in the form of sand.
Correct Answer is `=>` (A) silica
Q 2327067881

Match the following






Column I (Metallic oxide)Column II (Colour imparted to glass)
(A) Uranium oxide (1) Red
(B) Cuprous oxide (2) Blue
(C) Cobalt oxide (3) Green
(D) Chromium oxide (4) Yellow

NDA Paper 2 2011
(A)

4, 1, 2, 3

(B)

3, 2, 1, 4

(C)

4, 2, 1, 3

(D)

3, 1, 2, 4

Solution:

The colour of glass is due to the presence of metal ions (as oxides).








Metallic oxideColour of glass
Cuprous Oxide(`Cu_2O`) Red
Uranium oxide(`UO_2`) Yellow
Cobalt oxide(`CoO`) Blue
Chromium oxide(`Cr_2O_3`) Green
Correct Answer is `=>` (A) 4, 1, 2, 3
Q 2387578487

The reaction that takes place in soap making is called saponification. Basically soap is sodium or potassium salts of
NDA Paper 2 2011
(A)

long chain rnonocarboxylic acids

(B)

glycerol

(C)

long chain dicarboxylic acids

(D)

long chain tricarboxytic acids

Solution:

Soaps are sodium or potassium salts of higher fatty acids (or long chain monocarboxylic acids) such as lauric acid, `(C_11 H_23 COOH)`, palmitic acid `(C_15H_31 COOH)`, stearic acid `(C_17 H_35 COOH)`. e.g, of soap are sodium stearate `(C_17 H_35 COONa)`, sodium palmitate `(C_15 H_31 COONa)` etc.
Correct Answer is `=>` (A) long chain rnonocarboxylic acids
Q 2367491385

Iodised salt is a
NDA Paper 2 2010
(A)

mixture of potassium iodide and common salt

(B)

mixture of molecular iodine and common salt

(C)

compound formed by combination of potassium iodide and common salt

(D)

compound formed by combination of molecular iodine and common salt

Solution:

Mixture formed by combination of potassium iodide and common salt is known as iodised salt By the use of iodised salt we can prevent from goitre disease which is caused by the deficiency of iodine.
Correct Answer is `=>` (A) mixture of potassium iodide and common salt
Q 2337591482

By which one among the following mechanisms, soap removes dirt (soil) from cloth?
NDA Paper 2 2010
(A)

Soap dissolves the soil as such

(B)

Soap reacts with soil and converts them into soluble silicates

(C)

Soap takes away the oily part of the soil and thus separates the soil from the cloth

(D)

The soap molecules bind with the soil, lift the soil and keep it suspended which can then be rinsed away

Solution:

The soap molecules form micelle around the dirt particles and prevent them from coming together. Thus, an emulsion is formed between dirt particles and water which appears as foam. The hand rubbing or the agitation cause dispersion of the dirt particles throughout the soapy water. These are washed away with water along with dust particles. In this way dirt particles are removed from the surface of the cloth.
Correct Answer is `=>` (D) The soap molecules bind with the soil, lift the soil and keep it suspended which can then be rinsed away
Q 2308412308

The metal atom, which is present in super- phosphate, is

NDA Paper 2 2010
(A)

sodium (Na)

(B)

potassium (K)

(C)

calcium (Ca)

(D)

magnesium (Mg)

Solution:

The chemical formula of superphosphate is
`Ca(H_2PO _4 )_2` . Thus, calcium metal is present in superphosphate. It is prepared as
`Ca_3(PO_4)_2+2H_2SO_4-> Ca(H_2PO_4)_2+2CaSO_4`
Correct Answer is `=>` (C) calcium (Ca)
Q 2307323288


NDA Paper 2 2009

Assertion : On a wet floor of a bathroom, a small circular area around a pinch of foam appears to be dry.

Reason : Soap molecules reduce surface tension and increase surface area of the thin layer of water on the wet floor.

(A) Both A and R individually true and R is the correct explanation of A
(B) Both A and R are individually true but R is not the correct explanation of A
(C) A is true but R is false
(D) A is false but R is true
Solution:

On a wet floor of a bathroom, a small circular area around a pinch of foam appears to be dry because soap molecules reduce surface tension and increase surface area of the thin layer of water on the wet floor.
Correct Answer is `=>` (A)
Q 2317423389

Consider the following statements.
I. Soap cannot be used in acidic water.
2. Ionic part of a soap is `-COO^( -)Na^ +`.
3. Soap dissolves in water faster than detergent.
Which of the statements given above is/are correct?
NDA Paper 2 2009
(A)

1 and 2

(B)

2 and 3

(C)

Only 3

(D)

Only 1

Solution:

Soaps cannot be used in acidic solutions since acids precipitate the insoluble free fatty acids which adhere to the fabrics and hence, prevent the process of dyeing. A soap has a large non-ionic hydrocarbon group and an ionic group `-C O O^(-)Na^+` Detergents are more soluble in water than soaps.
Correct Answer is `=>` (A) 1 and 2
Q 2367434385

Match the following






Column IColumn II
(Material) (Important ingredient)
(A) Cement (1) Sodium salt of fatty acids
(B) Glass (2) Carbon black
(C) Ink (3) Silica in the form of quartz
(D) Soap (4) Aluminium and silicates of calcium

NDA Paper 2 2009
(A)

`A-> 4, quad B-> 3, quad C->2, quad D->1`

(B)

`A-> 1, quad B-> 2, quad C->3, quad D->4`

(C)

`A-> 2, quad B-> 3, quad C->4, quad D->1`

(D)

`A-> 4, quad B-> 1, quad C->2, quad D->3`

Solution:

Cement is essentially a finely powdered mixture of
calcium silicates and calcium aluminates with small amount of
gypsum.
Glass is a homogeneous mixture of silicates or borosilicates of
metals in silica in the form of quartz.
Carbon black is used in the manufacture of printer ink and carbon
papers.
Soap is the sodium sail of a long chain carboxylic acid (fatty
acid).
Correct Answer is `=>` (A) `A-> 4, quad B-> 3, quad C->2, quad D->1`
Q 2307534488

The metal compound commonly found in sindhoor or kumkum is based on.
NDA Paper 2 2009
(A)

tin

(B)

lead

(C)

copper

(D)

zinc

Solution:

Sindhoor or kumkum is red lead, `Pb_3O_4` , which is a
compound of lead (Pb). It is a mixture of lead monoxide and lead
dioxide `(PbO_2 * 2PbO)`. It is prepared by heating litharge in air at
`470°C`.

`6PbO+O_2 overset(470^o)-> 2Pb_3O_4`
Correct Answer is `=>` (B) lead
Q 2327634581

Which among the following elements (metals) pollutes the air of a city having large number of automobiles?
NDA Paper 2 2009
(A)

Cadmium

(B)

Lead

(C)

Chromium

(D)

Nickel

Solution:

Usually, tetra ethyl lead, `(C _2H _5)_4 Pb`, an antiknock compound, is mixed with petrol to improve its quality. Hence, automobile exhausts contain lead, which pollutes the air of the city.
Correct Answer is `=>` (B) Lead
Q 2377245186

Which one of the following chemicals is used in beauty parlous for hair-setting?
NDA Paper 2 2009
(A)

Sulphur based

(B)

Phosphorus based

(C)

Silicon based

(D)

Iron based

Solution:

Polysiloxane are usually used for hair setting in beauty parlous. These are silicon compounds which have an affinity for the hair and form a film at tile flair's surface. Due to this property these are used in hair setting.
Correct Answer is `=>` (C) Silicon based
Q 2377345286

Natural dye present in turmeric is called
NDA Paper 2 2009
(A)

cinnamin

(B)

phenolphthalein

(C)

methyl orange

(D)

curcumin

Solution:

Natural dye present in turmeric is called curcurnin
Correct Answer is `=>` (D) curcumin
Q 2367456385

Which one of the following is not a nitrogenous fertilizer?
NDA Paper 2 2008
(A)

`Ca(CN)_2`

(B)

`CaCN_2`

(C)

`NH_4NO_3`

(D)

Urea

Solution:

Plants take nitrogen in the form of nitrates which are
obtained from ammonia or nitrogen. Calcium cyanide is not a
nitrogenous fertilizer, as it does not give either ammonia or
nitrogen with water.

`Ca(CN)_2+H_2O-> HCN+Ca(OH)_2`

Calcium cyanamide, ammonium nitrate ancl urea produce
ammonia on hydrolysis

`CaCN_2 + 3H _2O -> CaCO_3 + 2NH _3`

`NH_4NO_3 + H _2O -> NH_3 + H_2O + HNO_3`

`NH _2CONH_ 2 + H _2O -> 2NH _3 + CO_2`
Correct Answer is `=>` (A) `Ca(CN)_2`
Q 2317556480

Flint glass is obtained from which of the following?
NDA Paper 2 2008
(A)

Zinc and barium borosilicate

(B)

Sand, red lead and potassium carbonate

(C)

Sodium aluminium borosilicate

(D)

Pure silica and zinc oxide

Solution:

Lead- potash lime glass is called flint glass. Its raw material are sand (`SiO_2`), red lead (`Pb_3O_ 4` ) and potassium carbonate (`K_2CO_3`). It has high refractive index and is used in making prisms, lens etc. It is a soft glass.
Correct Answer is `=>` (B) Sand, red lead and potassium carbonate
 
SiteLock