Chemistry Previous Year Questions of Laws of Chemical Combination and Gas Laws for NDA

Previous Year Questions of Laws of Chemical Combination and Gas Laws for NDA

Q 2734201152

Glass is a
NDA Paper 2 2017
(A)

liquid

(B)

colloid

(C)

non-crystalline amorphous solid

(D)

crystalline solid

Solution:


Correct Answer is `=>` (C) non-crystalline amorphous solid
Q 2118112909

Matter around us can exist in three different states namely, solid, liquid and gas. Correct order of their comprehensibility is.
NDA Paper 2 2016
(A)

Liquid < Gas < Solid

(B)

Solid < liquid < Gas

(C)

Gas < Liquid < Solid

(D)

Solid < Gas < Liquid

Solution:

The correct order of compressibility is Solid < Liquid < Gas.

Gases are highly compressible as compared to

solids and liquids. In gas, the molecules have enough

kinetic energy so that the effect of intermolecular

forces is small and the typical distance between

neighbouring molecules is much greater than the

molecular size.
Correct Answer is `=>` (B) Solid < liquid < Gas
Q 1678191906

Which one of the following weather conditions indicates a sudden fall in barometer reading?
NDA Paper 2 2015
(A)

Stormy weather

(B)

Calm weather

(C)

Cold and dry weather

(D)

Hot and sunny weather

Solution:

The word 'stormy' describes weather conditions like thunder, lightening, dark clouds, wind and pelting rain. This is the only option given in the question that indicates a sudden fall in barometer reading.
Correct Answer is `=>` (A) Stormy weather
Q 1678556406

A deep sea diver may hurt his ear drum during diving because of
NDA Paper 2 2015
(A)

lack of oxygen

(B)

high atmospheric pressure

(C)

high water pressure

(D)

All of the above

Solution:

In normal situations, the air inside your ear is at the same pressure as the air outside your ear. This means that the force on the two sides of the ear drum are the same and you are happy. But what if you go underwater? In this case, there is water on the outside of this ear drum, but air on the inside. If you don't do anything, the pressure inside will still be at atmospheric pressure. However, on the outside, the pressure will be greater. This means that the force from the inside air will not cancel with the pressure from the outside. Your ear drum doesn't want to accelerate, so it stretches like a spring to produces a net force of zero. This stretching of the ear drum hurts
Correct Answer is `=>` (C) high water pressure
Q 1884445357

Which one of the following weather conditions indicates a sudden fall in barometer leading?
NDA Paper 2 2015
(A)

Stormy weather

(B)

Calm weather

(C)

Cold and dry weather

(D)

Hot and Sunny weather

Solution:


Correct Answer is `=>` (A) Stormy weather
Q 2317491380

Calcium carbonate is naturally available as limestone and can also be synthesised from quicklime. It is seen that the compositions of the elements in both the natural and synthetic calcium carbonate are same. The validity of which one among the following laws is confirmed by this observation?
NDA Paper 2 2010
(A)

Law of conservation of mass

(B)

Law of definite proportion

(C)

Law of multiple proportion

(D)

Avogadro's law

Solution:

According to law of definite proportion, a chemical compound is always found to be made up of the same element combined together in the same fixed proportion by mass.
Correct Answer is `=>` (B) Law of definite proportion
Q 2337323282

According to which one of the following laws it is indicated that when two or more gases react with one another, their volumes bear a simple ratio?
NDA Paper 2 2009
(A)

Law of mass action

(B)

Law of multiple proportions

(C)

Law of reciprocal proportions

(D)

Law of combining volumes

Solution:

According to law of combining volumes, "When gases
react together, they always do so in volumes which bear a simple
ratio to one another and to the volumes of the products" This is
also known as Gay-Lussac's law of gaseous volumes.

e.g. `underset(1 vol)(H_2g)+ underset(1 vol)(Cl_2(g))-> underset(2 vol)(2HCl(g))`
Correct Answer is `=>` (D) Law of combining volumes
Q 2317834789

Two elements gallium and oxygen combine to form a compound `Ga _2O _3` . Which among the following is the valency of gallium?
NDA Paper 2 2009
(A)

1

(B)

2

(C)

3

(D)

4

Solution:

In a compound, the valency of an element
(electropositive element) is written as subscript of other element
(electronegative element) and vice-versa. Hence,

ln `Ga_2O_ 3`,

Valency of `Ga = + 3`

Valency of `O = -2`
Correct Answer is `=>` (C) 3
Q 2307645588

Each of the items consist of two statements, one labelled as the 'Assertion (A)'
and the other as 'Reason (R)'. You are to examine these two
statements carefully and select the answers to these items
using the codes given below.
NDA Paper 2 2008

Assertion : Carbon dioxide is a compound.

Reason : Carbon and oxygen combine together in the ratio `3 : 8` by mass.

(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:

Compound is a pure substance containing two or more
elements in a fixed ratio by mass. Carbon dioxide (`CO_2` ) is a
colourless gas. In `CO_2`

Mass of carbon `= 12 g`

Mass of oxygen `= 2 xx 16= 32`

`(text(Mass of carbon))/(text(Mass of oxygen))=12/32=3/8`

`:.` Carbon and oxygen combine together in the ratio of `3 : 8` by
mass in `CO_2`, hence !I is a compound.
Correct Answer is `=>` (A)
Q 2327567481

Which one of the following laws explains the formation of carbon monoxide and carbon dioxide from carbon and oxygen?
NDA Paper 2 2008
(A)

law of conservation of mass

(B)

Law of multiple proportions

(C)

Law of reciprocal proportions

(D)

Law of definite proportions

Solution:

Law of multiple proportions explains the formation of `CO` and `CO_2` from `C` and `O`. According to this law, if two elements combine in different ways to form different substances, their mass ratio are small whole number multiples of each other.

Thus, `(C : O text(mass ratio in CO))/(C : O text(mass ratio in )CO_2)=(12:16)/(12:32)=2`
Correct Answer is `=>` (B) Law of multiple proportions

 
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