Is Matter Around Us Pure, Science, Class 9 - Test - Class 9 MCQ

An anemometer is a device used for measuring wind speed, and is also a common weather station instrument. The term is derived from the Greek word anemos, which means wind, and is used to describe any wind speed instrument used in meteorology.

Sponge is compressible because it is having minute pores in which air is trapped .on pressing the air is expelled. it is still considered as a solid because it has a definite volume and shape does not changes unless compressed.

Alum can be separated from impure samples by the method of Crystallisation.
This method is based on the difference in the solubility of the compound and the impurities in a suitable solvent.
The impure compound is dissolved in a suitable solvent in which it is sparingly soluble at room temperature but appreciably soluble at higher temperature. The solution is concentrated to get nearly a saturated solution. Filtered the solution while hot if there is some undissolved impurities in the solution. When this saturated solution is cooled , crystals of pure alum will be separated out.

Thermometer is a temperature measuring device which consists of mercury.

The correct answer is 'C' because when we heat a liquid the space in between the molecule of liquid increases as some of the water gets evaporated and the solution becomes unsaturated.

Tyndall effect is the scattering of light by the particles of the mixture when passed through it. Tyndall effect is a characteristic property of colloids. Here, Starch solution is a colloidal solution. Hence, it shows tyndall effect.

Others like copper sulphate, sugar solution,sodium chloride are true solutions, hence don't exhibit tyndall effect.

Therefore, Starch solution shows tyndall effect.

Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties.

Fractional distillation is the process of separating two (or more) miscible liquids by distillation, the distillate being collected in fractions boiling at different temperatures.This separation depends on the boiling point of the two liquids.It is carried by using a fractionating column.

Centrifugation is the process where a mixture is separated through spinning. It is used to separate skim milk from whole milk, water from your clothes, and blood cells from your blood plasma. Although centrifugation is primarily used to separate mixtures, it is also used to test the effects of gravity on people and objects.