Mixture

Q.

Air is a mixture but not a compound. Explain why?

Q.

Is Common salt a mixture or a compound? Why?

Q.

Why do we need pure substance for our use?

Q. The physical combination of two or more substances is known as.

1. mixture
2. compound
3. element

Q.

Which is a pure compound?

Q. Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then a small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured​

crystals got separated (step II). Step I and step II are:​

1. physical and chemical changes respectively.​
2. chemical and physical changes respectively.​
3. both physical change.​
4. both chemical change.​

Q.

All mixtures have a uniform composition.

1. True

2. False

Q.

Constituents of ANY mixture can be separated by physical methods.

1. True

2. False

Q.

Salt solution is a__________________ mixture.

Q.

The gas present in the atmosphere which is essential for respiration of plants is

1. Oxygen

2. Carbon dioxide

3. Nitrogen

4. Plants don't breath.

Q.

State the main components of bronze.

Q.

In a colloidal system called gel, the dispersed phase is ________ and dispersion medium is ________

Q.

5. Give two reasons to support that air is a mixture.

Q.

Give one example of a liquid in a solid (homogenous).

Q.

In what properties of the constituents are retained?

Q.

Give two characteristics of a chemical compound.

Q.

State the differences between compounds and mixtures with an example of each. [3 MARKS]

Q.

How will you justify that clean air is a mixture and not a compound?

Q.

A mixture has a definite set of properties.

1. True
2. False

Q.

All mixtures are homogeneous in nature.

1. True
2. False

Q.

Sodium chloride is a mixture of sodium and chlorine.

1. True
2. False

Q. Is milk pure? Why ?

Q. Seawater is not used for drinking purposes because:

1. it is salty
2. it is poisonous
3. it is not good for health
4. it supports aquatic life

Q.

What do you understand by the term mixture?

Q. Which of the following is not an element?

1. Sodium
2. Gold
3. Soil
4. Carbon

Q.

Air is a mixture of gases

1. True
2. False

Q.

Classify the following substance as element, compound or mixture:

Iodised salt

Q. Mixtures are impure and hence comprises of different

1. Melting point.
2. Boiling point.
3. Densities.
4. None of these.

Q.

Give the name of two main constituents of air.

Q.

Which of the following is the major constituent of air?

1. Oxygen

2. Nitrogen

3. Carbon dioxide

4. None of these