# NCTB Class 7 science Chapter 7“Properties of Matter and external Effect” Solution

Bangladesh Board Class 7 science Solution Chapter 7“Properties of Matter and external Effect” Exercises Question and Answer by Experienced Teacher.

## NCTB Solution Class 7 Chapter 7 “Properties of Matter and external Effect”

 Board NCTB Bangladesh Board Class 7 Subject science Chapter Seven Chapter Name “Properties of Matter and external Effect ”

 Left Right Every matter Do not conduct heat Sound Is not matter Solid Has definite size and volume Metals on strike Do not break

(1) Answer:- The characteristics of matter:

(i) Volume and definite size: A solid body has volume and definite size because it occupies space.

(ii) Rigidity and flexibility:- Some matters are soft, some are hard, some are flexible and some are nonflexible.

(iii) Electrical conductivity:- Metals conduct electricity. The bulb is illuminating. As copper is an electricity taking from the cell and send it to the bulb lights up.

(iv) Melting point and boiling point:- The temperature at which water begins to vaporise is called the boiling point of water. Similarly the temperature vat which ice begins to melt is called the melting point of ice.

(2) Answer:- No, light is not one kind of matter. Because matters are solid, liquid and gas, but light does not belong to one of these. Light is just a form of energy.

The main differences among solid, liquid and gaseous substance are—

 Solid Liquid Gas (i) It has a definite size. (i) Its size is changeable (i) It has no size (ii) It has less rigidity. (ii) It has no rigidity. (ii) It has no rigidity.

(3) Answer:- Copper is used in electric wires because copper is an electric conductor. In bulb, copper wires transmits electricity taking from the cell and send it to the bulb and the bulb lights up.

(4) Answer:- Melthing point: The temperature at which solid begins to melt is called the melthig point of that solid.

Boiling point: The temperature at which liquid begins to that liquid.

### (1) Answer:- (c) Banana- has less rigidity.

(2) Answer:- (b) Scent- When kept in a bottle, occupy the entire space of the bottle.

(3) Answer:- The object used by (b) Mathin’s father as shown in the table is an electric and conductor.

#### Creative questions:-

(1) (a) Answer:- That things which occupy space and have mass are called matter.

(1) (b) Answer: The things which do not conduct heat or electricity do not have definite size and volume like metal are called non-metal.

(2) (a) Answer:- The temperature at which liquid begins to vaporise is called the boiling point of that liquid.

(2) (b) Answer:- Thermal conductivity is a rate of heat which a metal can conduct in a particular time.

(2) (c) Answer:- The substance shown in fig x can be converted fig Y at its melting point and the Y can be converted into fig-Z at its boiling point. That’s how the substance shown in fig x can be converted into fig-z.

Updated: December 23, 2020 — 11:23 am