Q1. Helium is preferred to hydrogen in air balloons because it
(a) is cheaper
(b) is less dense
(c) has greater lifting power
(d) does not form an explosive mixture with air
(e) None of the above
Q2. In which one of the following situations a chemical reaction does not occur?
(a) Common salt is exposed to air
(b) Coal is burnt in air
(c) Sodium is placed in water
(d) Iron is kept in moist air
(e) None of the above
Q3. Oils are purified by
(a) Fractional distillation
(b) Steam distillation
(c) Crystallisation
(d) Vacuum distillation
(e) None of the above
Q4. Which of the following has the largest number of chromosomes?
(a) Human beings
(b) Pteridophytes
(c) Elephants
(d) Bryophytes
(e) None of the above
Q5. The phenomenon of genetic mutation can not occur in
(a) DNA
(b) RNA
(c) chromosome
(d) ribosome
(e) None of the above
Q6. The main function of the Golgi body is
(a) respiration
(b) to begin cell division
(c) to produce gastric juice
(d) secretion
(e) None of the above
Q7. The torque produced by a force depends on
(a) The magnitude of the force
(b) The direction of the force
(c) The point of application of the force relative to origin
(d) All of the above
(e) None of the above
Q8. Which of the following could act as a propellant for rockets?
(a) Liquid oxygen + Liquid argon
(b) Liquid hydrogen + Liquid oxygen
(c) Liquid nitrogen + Liquid oxygen
(d) Liquid hydrogen + Liquid nitrogen
(e) None of the above
Q9. Which one of the following mixtures is homogeneous?
(a) Starch and sugar
(b) Methanol and water
(c) Graphite and charcoal
(d) Calcium carbonate and calcium bicarbonate
(e) None of the above
Q10. What would be the best choice for window material to keep the outside heat away?
(a) Single-pane glass
(b) Double-pane glass without a gap in between
(c) Double-pane glass with water filled in between
(d) Double-pane glass with air in between
(e) None of the above
Solutions
S1.Ans. (d)
Sol. Hydrogen combines with oxygen with explosive force in the presence of a spark. Helium is an inert gas that will not burn or explode, so is much safer to use in balloons instead of hydrogen.
S2.Ans. (a)
Sol. Exposure of common salt to air is a physical change. In chemical sections, reactants produce substances which are different form the reactants No chemical realize taken plot when common salt (NaCl) is exposed to air as no new substances are produced.
S3.Ans. (b)
Sol. Oils are purified by steam distillation. In steam distillation process steam is bubbled through a heated mixture of raw material. Some of the target components will vaporize which are coded and condensed yielding a layer of oil and a layer of water.
S4.Ans. (b)
Sol. Ferns, a group under pteridophytes have large number of chromosomes e.g., Ophioglossum reticulatum has 2n=1260, highest known in all life forms.
S5.Ans. (d)
Sol. The ribosomes are the protein-synthesizing factories. DNA, RNA and chromosomes are all genetic materials made of nucleotides, which are the sites of genetic mutations e.g., transversion and transition, point mutations, etc. DNA, RNA are genetic material which helps in replication of genetic material, while chromosomes are the part of DNA.
S6. Ans. (d)
Sol. The Golgi complex and rough ER work closely. When a protein is made in the ER, then transition vesicles are synthesized. These vesicles float through the cytoplasm to the Golgi apparatus and are absorbed. After the Golgi does its work on the molecules inside the sac or the vesicle a secretory vesicle is created and released into the cytoplasm. So the main function of the Golgi bodies is secretion.
S7.Ans. (d)
Sol. Torque is the cross product of force and perpendicular distance to an axis of rotation. The torque produced by a force depends on the magnitude of the force, the direction of the force, the point of application of the force relative to origin.
S8.Ans. (b)
Sol. Liquid hydrogen and liquid oxygen are used as excellent fuel for rockets. H2(l) has low mass and high enthalpy of combustion whereas oxygen is a strong supporter of combustion.
S9.Ans. (b)
Sol. Homogeneous miniature have the Same composition throughout. A mixture of methanol (a liquid) and water (a liquid) is homogeneous.
S10.Ans. (d)
Sol. To keep the outside heat away, windows of double-pane glass with air in between is the best choice because air is the bad conductor of heat.