NCERT Solutions for Class 6 Science Chapter 6

1. Iron rim is made slightly smaller than the wooden wheel. The rim is usually heated before fixing into the wooden wheel, because on heating the iron rim
(a) expands and fits onto the wooden wheel.
(b) contracts and fits onto the wooden wheel.
(c) no change in the size takes place.
(d) expands first, then on cooling contracts and fits onto the wooden wheel.
2. An iron ring is heated. Which of the following statement about it is incorrect?
(a) The ring expands.
(b) The ring almost comes to the same size on cooling.
(c) The change in this case is reversed.
(d) The ring changes its shape and the change cannot be reversed.
3. Pick the change that can be reversed from the following
(a) Cutting of trees
(b) Melting of ghee
(c) Burning of candle
(d) Blooming of flower
4. While lighting a candle, Paheli observed the following changes
(i) Wax was melting.
(ii) Candle was burning.
(iii) Size of the candle was reducing.
(iv) Melted wax was getting solidified.
5. Rolling of chapati and baking of chapati are the changes that
(a) can be reversed.
(b) cannot be reversed.
(c) can be reversed and cannot be reversed, respectively.
(d) cannot be reversed and can be reversed, respectively.
6. Which of the following change cannot be reversed?
(a) Hardening of cement (b) Freezing of ice cream (c) Opening a door (d) Melting of chocolate
7. Salt can be separated from its solution (salt dissolved in water), because
(a) mixing of salt in water is a change that can be reversed by heating and melting of salt.
(b) mixing of salt in water is a change that cannot be reversed.
(c) mixing of salt in water is a permanent change.
(d) mixing of salt in water is a change that can be reversed by evaporation.

1 (d),
2 (d),
3 (b),
4 (d),
5 (c),
6 (a),
7 (d).
All answers are done properly based on new CBSE Syllabus and following the latest NCERT Books.