grade 7

poisonous gases that affect on both eyes and the nervous system is nitro oxides

• true

• false

the bond in a molecule of magnesium oxide is an ionic bond

• because magnesium loses 2 electrons and oxygen gains 2 electrons

• because magnesium loses 1 electron and oxygen gains 1 electron

electromagnet is used in making ...

• electric bells

• electric winches

• all of the above

the ability of the earth to attract an object to its center is friction force

• true

• false

the only non metal exists in a liquid state

• mercury

• bromine

• sulfur

• carbon

the valency of calcium is

• 2

• 3

• 4

• 1

the ...... bond in oxygen

• ionic

• single covalent

• double covalent

• triple covalent

burning of coal causes ..... pollution

• air

• electromagnetic

• noise

water wave is an example of periodic motion

• true

• false

electric fan works for second after cutting of electric current due to force of inertia

• true

• false