Explore topic-wise InterviewSolutions in Current Affairs.

Air is a mixture because it has many gases in indefinite ratio.

1. Element – copper, hydrogen.

2. Mixture – brass, sand.

Element: The atoms of an element are similar in their properties.

For examples iron, copper, aluminium, gold etc. 

Compound: When two or more atoms combine through a chemical reaction in a fixed ratio, a compound is formed.

For example, sugar, glass, salt, soap, etc.

Mixture: Mixture is a substance which is formed when two or more compounds or elements are mixed in any ratio.

For example, sharbet, air, sand, etc.

Element – Oxygen gas, iron, hydrogen gas, brass. 

Compound – Sugar, salt, soap, surf.

Mixture – Syrup, sharbet, air.

Five compounds used in our daily life are 

1. Common salt 

2. Water 

3. Soap 

4. Baking soda 

5. Sugar

The undivided particle of substance is known as atom. We cannot see those atoms through naked eyes. Atom is made up of three particles proton, electron and neutron.

The central part of an atom is called nucleus.

(d) Proton and neutron

Greek philosopher Demokrits name the undivided particle of substance as atom. 

An atom is made up of three particles: 

1. Proton (p) 

2. Electron (e)

3. Neutron (n) 

An atom has two structural parts

1. Nucleus (inner part) 

2. Electric shell (outer part) 

The inner part of atom is called Nucleus. It has two particles: 

1. Proton (p) – It is positively changed.

2. Neutron (n) – It is electrically neutral. 

The outer part of atom consist of negatively charged particles called electron (e). They, circulate around nucleus in definite orbits.

Five Compounds and their Formula.

Correct Answer is: (a, c)

Let R₁ and R₂ be the resistances of the two heaters.

Let H be the heat produced.

∴ H =  (V²/R₁) t₁ = (V²/R₂) t₂.

When used in series, H = (V²/R₁ + R₂) t.

When used in parallel, H = (V²/R₁ + V²/R₂) t.

Plasma is a saturated gaseous state. This state is found in sun, stars, tube-lights and picture tubes of T.V

In vedic period, the great philosopher Kanad authored Veseshik Sutra which is basic nuclear physics for Scientists of West. He propounded the atomic theory of Veseshik philosophy. He gave the concept that atom combines together to make molecules. He ateTandual particles (Sama rice in Hindi) during his meditation that made his name ‘Kanad’. He was the originator of the particle-molecule theory and hence called as Kanad.

The approximate size of Parmanu is 10^-10 m.

Indian philosopher Maharishi Kanad

The molecular formula of water is H₂O.

Correct Answer is: (a, c,& d)

The answer is (A) 500 BC

A mixture of Kerosene oil and water is a heterogeneous mixture.

There are four significant figure exist in 1.040 x 10³.

(a) (i) 0.0026 = 2.6 × 10^–3

It has two significant figures.

(ii) 6.022 × 10¹³

It has four significant figures.

(b) Number of particles in a mole = 6.023 × 10²³

Molecular mass of C₆H₁₂O₆ = 180

Number of carbon atoms = 6

\(\therefore\) 180 g of C₆H₁₂O₆ contains

= 6 × 6.023 × 10²³ carbon atoms

\(\frac{6\times6.023\times10^{23}\times34.20}{180}\)

= 6.866 × 10²³ carbon atoms

The answer is (C) 3

By Filtration method we would separate the water from sandy water.

Correct Answer is:(a) a³R/6b

Q = at - bt².

i = dQ dt = a - 2bt.

i = 0 for t = t₀ = a/ 2b, i.e., current flow from t = 0 to t = t₀.

The heat produced = i²R dt. for t ∈ [0, t₀]

The atomicity of oxygen in dioxygen is Two.

An example of a monoatomic molecule is Argon.

Solid state is the state of matter in which shape and volume are definite.

Compressed Natural Gas

A pure substance consists of a single type of particles and all the constituent particles of that substance are the same in their chemical nature.

Evaporation is the process in which liquid is converted into vapours.

Amount of heat energy required to change 1 kg of a liquid into a gas at atmospheric pressure at its boiling point is known as the latent heat of vaporisation of that liquid.

An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

The answer is (C) Gases and liquids behave like fluids.

Element: An element is the basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Compound: It is a substance made up of two or more elements chemically combined with one another in a fixed ratio.

The answer is (D) A mixture of a solid in another solid

The answer is (C) loading

The melting point of ice is 0°C or 273 K.

The melting point of a solid is the temperature at which it changes the state from solid to liquid at atmospheric pressure.

The answer is (A) heating

In a pure substance, all the constituent particles are the same in their chemical nature. But most of the matter we see and use is constituted by more than one kind of pure substances and are known as mixtures. For e.g. milk is actually a mixture of water, fat, proteins etc. Seawater, sugar, minerals, soil, nylon, cotton, oil, paper, air etc. are all mixtures. Mixtures may be homogeneous or heterogeneous.”

The fractionating column is fitted in a distillation apparatus between the distillation flask and the water condenser.

The answer is (C) Steel

The answer is (B) is used to overcome the forces of attraction between the particles

(1) Liquids do not have fixed shape but have fixed volume: The inter-particle forces of attraction in liquids are weaker than the inter-particle forces between the particles in the solid state. However, the inter-particle forces are stronger, as compared to inter-particle forces in gases. Therefore, particles in a liquid are not fixed at their positions and can move, yet the inter-particle forces do not allow the particles to go beyond a definite limit. This keeps the volume of the liquid, constant, even when its shape is changing. Therefore, liquids do not have fixed shape and can acquire the shape of the container, in which it is kept. However, the volume of the liquid remains the same. 

(2) Liquids have lower density: As the inter-particle forces of attraction is weaker in liquids than in solid state. Thus, the number of particles per unit volume is less, which accounts for the lower density of liquids, when compared to solids. 

(3) Liquids can diffuse: As the inter-particle forces in liquids are not strong enough to keep them in fixed positions, thus, the particles may flow and this accounts for the fact, that liquids can diffuse. 

(4) Liquids are compressible: As the particles in a liquid can move, thus the volume of liquids can change and so, they are compressible in nature.

The answer is (C) Formation of clouds

The answer is (D) Solution

The changes which occur without a change in composition and in chemical nature of the substance are called physical changes. 

For example: The change of water in ice is a physical change because chemically, ice and liquid water both are same. 

These changes are mostly reversible in nature i.e. the original substance can be further obtained by reversing the reaction conditions.

The answer is (B) Rusting of iron

The answer is (A) Colour

The answer is (C) Oxygen, Water, Sugar