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NDA General Science Previous Year Questions


Q1.
Which one of the following is the correct statement? Graphite can be used as lubricant because it has:
(a) a rigid structure
(b) low viscosity
(c) layered structure
(d) low melting point 4. The oxide of which of the following elements is used as a coolant?

Q2. The main constituent of vinegar is
(a) Citric acid
(b) Acetic acid
(c) Ascorbic acid
(d) Tartaric acid

Q3. Which one of the following is the correct order in which the gases H2, Ne, O2 and N2 are evolved on fractional distillation of liquid air?
(a) H2, Ne, O2, N2
(b) H2, Ne, N2, O2
(c) N2, O2, Ne, H2
(d) O2, N2, H2, Ne

Q4. Which of the following represent a chemical change?
 1. Magnetization of iron
 2. Condensation of liquid
 3. Burning of fuel
 4. Rusting of iron
Select the correct answer using the code given below:
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 4

Q5. When a copper rod is dipped in aqueous silver nitrate solution, the colour of the solution changes to blue. This is because
(a) Cu is more easily reduced than Ag
(b) Ag is more easily reduced than Cu
(c) Nitrate ion acts as an oxidizing agent
(d) Nitrate ion acts as a reducing agent

Q6. Which one of the following is used as a fertilizer?
(a) NH4OH
(b) NH4Cl
(c) NH4NO3
(d) (NH4)2SO4

Q7. Which of the following chemicals is used in foam fire extinguishers?
(a) Aluminium sulphate
(b) Copper sulphate
(c) Cobalt sulphate
(d) Nickel sulphate

Q8. Consider the following statements
1. Soap cannot be used in acidic water.
2 Ionic part of a soap is —COO– • Na+.
3. Soap dissolves in water faster then detergent.
 Which of the statements given above is/are correct?
(a) 1 and 2
(b) 2 and 3
(c) 3 only
(d) 1 only

Q9. Sodium stearate is a salt and is used
(a) in gunpowder
(b) in paint
(c) to make soap
(d) to make fertilizer

Q10. An oxidising agent is a substance which
(a) increases the oxidation number of an element in a given substance
(b) decreases the oxidation number of an element in a given substance
(c) is oxidised itself in an oxidation reduction reaction
(d) loses electrons in an oxidation-reduction reaction

Q11. Why doesn’t Archimedes’ principle hold for a vessel under a free fall?
(a) The effective value of g increases
(b) The effective value of g decreases
(c) The body immersed in the vessel will become weightless
(d) The density of air increases

Q12. When oil floats on water, the surface tension of water
(a) vanishes immediately
(b) decreases considerably
(c) increases considerably
(d) remains unaffected

 1. (c)2. (a)3. (b)4. (c)5. (b)6. (d)7. (a)8. (a)9. (c)10. (a)11. (c)12. (b)

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