31.

Which of the following effect is not found in sound waves?

• Polarisation

• Reflection

• Interference

• Diffraction

Energy equivalent to 1 amu is

• 0.693 MeV

• 1 eV

• 931 MeV

• 14.2 MeV

Which one of the following is not a characteristic of thermal radiation?

• It does not require medium for its propagation

• It travels with velocity of light

• It travels in straight line

• It affects the medium through which it propagates

Which of the statements about the reaction given below are incorrect?

2 PbO(s) + C (s) → 2Pb (s) + CO₂(g)

1. Lead is getting reduced.
2. Carbon dioxide is getting oxidised
3. Carbon is getting oxidized.
4. Lead oxide is getting reduced

• (i) and (ii)

• (i) and (iii)

• (i), (ii) and (iii)

• All of these

Write the products of the following chemical reaction

$2 {\mathrm{FeSo}}_4 · 7{\mathrm{H}}_2\mathrm{O} \stackrel{∆}{\to } \mathrm{M} \stackrel{∆}{\to } \mathrm{X} + \mathrm{Y} + \mathrm{Z}$

• M = FeSO₄, X = FeO, Y = SO₂, Z= SO₃

• M = Fe₂(SO₄)₃, X = Fe₂O₃, Y = SO₂, Z= H₂O

• M = FeSO₄, X = Fe₂O₃, Y = SO₂, Z = SO₃

• M = Fe₂ (SO₄)₃, X = FeO, Y = SO₂, Z = H₂O

Latent heat of vaporization is

• the heat energy required to change 10 g of liquid to a gas at atmospheric pressure at its boiling point

• the heat energy required to change 1 L of liquid to a gas at atmospheric pressure at its boiling point

• the heat energy required to change 1 mL of liquid to a gas at atmospheric pressure at its boiling point

• the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point

Identify the incorrect statement about the nature of science.

• Speculation and conjecture also have a place in science, but ultimately a scientific theory, to be acceptable, must be verified by relevant observations and/or experiments

• Science is considered as value-neutral and objective, and the laws of science are viewed as fixed

• The methodology of science and its demarcation from other fields continue to be a matter of philosophical debate

• Even the most established and universal laws of science are always regarded as provisional, subject to modification in the light of new observations, experiments and analyses