Select the correct answer from the choice in bracket to complete each sentence

1. Dust in air is an example of …………… [heterogeneous/homogeneous] mixture.

2. A soluble solid is separated from an insoluble solid by …………… [fractional crystallisation / solvent extraction].

3. The reactive element from the two monoatomic elements is …………… [neon/silicon].

4. Compounds are …………… [homogeneous or heterogeneous/ always homogeneous] in nature.

5. An example of a monoatomic molecule is …………… [hydrogen/helium].

Give reasons for the following statements:

1. Components in a mixture can be separated by physical methods only.

2. Centrifugation can be used for separating an insoluble heavier solid, present in an insoluble solid-liquid mixture.

3. The filter paper made into a cone & placed in a funnel for filtering out the solid particles in a solid-liquid mixture, should be moistened before placing.

4. Brass & bronze are examples of mixtures, while copper sulphate & lead nitrate are examples of compound.

5. Zinc is considered an element, while zinc sulphide is considered a compound.

The diagram represents fractional distillation for separation of mixtures. Answer the following:

1. Can two immiscible liquids be separated by this process.

2. Separation of liquids by this process is based on which physical property.

3. If methyl alcohol & water are to be separated, which liquid would remain in flask 'X' after condensation.

4. Give a reason for the above answer.

5. State the purpose of the fractionating column in the apparatus.

Select the correct answer from A, B, C, D & E for each statement given below:

A: Gunpowder

B: Iodine

C: Boron

D: Helium

E: Bromine

1. A diatomic molecule

2. A metalloid

3. A non-metal which is lustrous

4. A mixture consisting of elements & a compound

5. A noble gas