Question with Answer NSO Science

A student wrote three statements about rancidity :

I. When fats and oils are reduced, they become rancid.

II. Chips manufacturers usually flush chips bags with oxygen to prevent rancidity.

III. Rancidity is prevented by adding substances called antioxidants to food.

Choose the correct statement(s) :

(a) I

(b) II and III

(c) III

(d) I, II and III

Ans (c)

1. Metal X is found in earth’s crust. This metal forms a reddish brown powder when exposed to moist air. When a blue coloured solution Y is stored in a container made of X, the solution turns green and reddish brown metal Z is deposited on the container.

X, Y and Z respectively are

(a) Cu, CuSO 4 , Fe

(b) Zn, ZnSO 4 , Fe

(c) Fe, CuSO 4 , Cu

(d) Cu, FeSO 4 , Fe

Ans (c)

1. A student added dilutr HCL to a test tube containing zinc granules. Which of the following observations are correct ?

I. Zinc surface became dull and black.

II. A gas was evolved which burnt with a pop sound.

III. The solution remained colourless.

(a) I and II

(b) I and III

(c) II and III

(d) I, II and III

Ans (d)

1. Which of the following reactions are exothermic in nature ?

(i) Evaporation of water (ii) Dissolution of sodium hydroxide in water

(iii) Dilution of sulphuric acid (iv) Dissolution of ammonium chloride in water

(v) Combustion of methane gas

(a) (i), (iv) and (v)

(b) (ii), (iii) and (v)

(c) (i), (ii) and (iv)

(d) (i), (iii) and (iv)

Ans (b)

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