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Magnesium oxide cannot be reduced by normal reducing agents.

(a) A metal which occurs as sulphide is lead.

(b) A metal which occurs as halide is silver.

(c) A metal which occurs as carbonate is zinc.

(d) A metal which occurs as oxide is iron.

Three tests are:

HCl gas gives thick white fumes of ammonium chloride when glass rod dipped in ammonia solution is held near the vapors of the acid.

NH₃ + HCl ⟶ NH₄Cl

With silver nitrate HCl gives white precipitate of silver chloride. The precipitate is insoluble in nitric acid but soluble in ammonium hydroxide.

AgNO₃ + HCl ⟶ AgCl + HNO₃

A greenish yellow gas is liberated when concentrated hydrochloric acid is heated with oxidizing agent like manganese dioxide.

MnO₂ + 4HCl ⟶ MnCl₂ +2H₂O + Cl₂

Magnesium Nitride

(i) Ethyne 

(ii) Acetic acid 

(iii) Ethene 

(iv) Ethanol

(i) Barium Chloride 

(ii) Platinum 

(iii) Coke 

(iv) Acetylene 

(v) Bronze

Because on cooling below its melting point (17^oC), it solidifies and forms little ice-like crystals.

(i) ₁₉E is a metal.

₈F and ₁₇G are non-metals.

(ii) Molecular formula - EG. 

Type of bond - Ionic bond.

E = 19 = 2, 8, 8, 1

F = 8 = 2, 6

G = 17 = 2, 8, 7 

(i) E = Metal, F & G = Non metal

(ii) E⁺¹XG^-1 = EG = lonic/electrovalent bond

Because on cooling pure acetic acid forms ice like crystals.

1. metallic 

2. smallest.

When ethene is oxidised, ethanol (C₂H₅OH), ethanal (CH₃CHO) and ethanoic acid (CH₃COOH) are formed.

Ba will form ions most readily because it has lowest ionisation potential in group 2

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Electronegativity of an element is its relative tendency to attract the shared pair of electrons towards itself in a covalent bond.

1. ethane → substitution reactions 

2. ethene → addition reactions.

(i) Cryolite 

Molten cryolite acts as solvent for alumina,lowers the fusion temperature from 2050^oC to 950^oC and enhances conductivity. 

(ii) Al³⁺ + 3e^- ----> Al. 

(iii) During electrolysis oxygen gas is formed at anode which oxidises graphite anode to carbon dioxide, so it is necessary to replace anode periodically.

(i) In nuclear fission and fusion there is a loss in mass due to loss in mass energy is released. The energy so released is called the nuclear energy. 

(ii) Nuclear fission.

An ideal machine works on the principle that work input = work output and has 100% efficiency as there is no energy loss.

OR

Work done by the machine = Work done on the machine.

When a body is vibrating freely with constant amplitude of oscillation is called free vibration of a body.

(i) Free vibrations are produced when a body is disturbed from its equilibrium position and released.

(ii) Body continuously losses energy due to frictional force of the surrounding medium in damped oscillations, therefore amplitude of body continuosly decreases.

Work is said to be done when the applied force produces displacement in the direction of the force.

Work done = Force x Displacement

Work done is zero by the moon, as there is no displacement since it is moving in a circular path.

(i) Work is said to be done only when the force applied on a body makes the body moves (i.e., there is displacement of the body). 

(ii) The work done by the moon when it revolves around the earth is zero.

(i) Electrical energy converted to sound energy. 

(ii) Electrical energy converted to light and heat energy.

(i) Loud speaker : Electrical energy to sound energy.

(ii) Glowing electric bulb : Electrical energy to heat and light energy.

(i) E_S/ E_P=N_S/ N_P Here e.m.f. is directly propotional to number of turns. 

(ii) Transformer works on alternating current or A.C. current.

(i) Nuclear energy is the energy released by the atom's nucleus during a nuclear reaction.

(ii) Nuclear fission.

The conversion of part of the energy in to an undesirable form is called Dissipation of energy.

When there is a damping force acting on vibrating body, then amplitude of vibration decreases due to damping force such vibration is called damped vibration.

 The amplitude of a vibrating body continuously decreases during damped vibrations because of the frictional (resistive) force due to the surrounding medium.

Advantages on producing electricity by Nulcear fusion are: 

(i) No toxic waste are produced. 

(ii) No radioactive radiation produced. 

(iii) Nuclear fusion power plant can be located near the populated areas. 

(iv) We produce large amount of energy by consuming simple Hydrogen gas.

The periodic vibrations of a body in the absence of any external force on it, are called free (or natural) vibrations.

Advantage: A very small amount of nuclear fuel can produce a tremendous amount of electricity energy. 

Disadvantage: Very harmful nuclear radiations are produced in the process which are highly energetic and penetrating.

Nuclear fusion is not possible at ordinary temperature and ordinary pressure, but the advantage of fusion reaction over fission reaction is that the fusionable substance is not radioactive, so it does not give out any harmful radiations and the disposal of its waste is not difficult.

Nuclear fusion is the process in which two light nuclei combine to form a heavy nucleus. In this process, huge amount of energy is released.

This is not an alloy of copper Solder.

Bonding in this molecule can be understood to involve coordinate bonding Ammonium chloride.

(D) Ammonium chloride

(D) 6.02 x 10²³ atoms of carbon

(D) 6.02 x 10²³ atoms of carbon

32 gm of Sulpher = 1 mole

3.2 gm of Sulphur = \(\frac{1}{32}\times3.2 \)

= 0.1 moles

At. Mass of Calcium = 40

∴ mass of 0.1 mole of Ca = 40 x 0.1 = 4 gm

32 gm of sulphur contain = 6.023 x 10²³ atoms

3.2 gm of sulphur contain = (6.023 x 10²³)/32 x 3.2 = 6.023 x 10²²

Now, 6.023 x 10²³ atom of calcium have mass = 40 g

6.023 x 10²² atoms of calcium have mass = 40/(6.023 x 10²³) x (6.023 x 10²²) = 4 g

Hence, the mass of calcium is 4 g.

(i) The blue coloured copper nitrate crystals changes into black powdery mass with the release of reddish brown NO₂ gas. 

(ii) The reddish brown colour of bromine water disappears. 

(iii) Lead acetate solution becomes black due to the formation of lead sulphide. 

(iv) Ammonia burns with a yellowish green flame in the atmosphere of excess oxygen. 

(v) The copper of the anode dissolves and, therefore, it becomes thin gradually.

(i) Nitric acid 

(ii) Conc. sulphuric acid 

(iii) Nitric acid 

(iv) Sulphuric acid 

(v) Hydrochloric acid.

This is because of the absence of free ions in the carbon tetrachloride molecule.

This is because of the fact that aluminium has great affinity towards oxygen and so aluminium oxide cannot be reduced by reducing agents such as carbon monoxide or carbon or hydrogen.

1. Zinc is comparatively less reactive. So its oxideis less stable and hence it can be reduced by reducing agent whereas Aluminium is very reactive due to which its oxide is quite stable and it can not be reduced by a reducing agent it can be reduced only by electrolytic reduction. 

2. Carbon tetrachloride is a non polar covalent compound and so do not have free ions therefore they do not conduct electricity. 

3. Graphite is an inert electrode which is preferred in electrolysis of molten lead bromide because if other active electrodes are used then bromine will react with them. 

4. Acetic acid is a weak acid and has less number ions so conductivity is less whereas dil. sulphuric acid is a strong acid, has more number of ions and thererfore its electrical conductivity is more.

5. During electrolysis of molten lead bromide lead gets oxidised and bromine gets reduced. Thus both oxidation and reduction occur simultaneously. So it is a redox reaction.