Q1. Hydrogen bomb is based on the principle of—
(a) controlled fusion reaction
(b) uncontrolled fission reaction
(c) controlled fission reaction
(d) uncontrolled fusion reaction
Q2. Which gas emits from the rice field?
(d) All of the above
Q3. Pyrethrin used in mosquito coil is obtained from which of the following?
(a) a bacterium
(b) an insect
(c) a seed plant
(d) a fungus
Q4. The blue colour of water in the sea. What is the reason behind the phenomenon?
(a) Refraction of the blue light by the impurities in sea water.
(b) Absorption of other colours except the blue colour by water molecules
(c) Refraction of blue sky by sea water.
(d) Scattering of blue light by water molecules.
Q5. Which of the following is the end product of alcoholic fermentation?
(a) pyruvic acid
(b) ethyl alcohol
(d) formic acid
Q6. When iron is rusted, it is—
Q7. Blood cells do not shrink in blood because blood is—
Q8. Oils are purified by
(a) Fractional distillation
(c) Steam distillation
(d) Vacuum distillation
Q9. The deficiency of which one of the following leads to dental caries?
Q10. Alum purifies muddy water by which process?