Is Matter Around Us Pure Test - 8

An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions. Elements include metals, non-metals and semi-metals (metalloids). Alloys are mixture of two or more elements.

Metals are sonorous i.e. metals produce sound when hit with an object. So, A hard substance when bent produces a tinkling sound is metal. Non-metals are non-sonorous

Mercury is a thick shining liquid used commonly in glass thermometer. It does not stick with wall and expands uniformly on heating.

A compound is a substance formed when two or more elements are chemically bonded together. The property of compound has always different from its constituents.  It has a fixed composition.  The constituents of compound can be separated by chemical or electrochemical reactions. During chemical reaction heat is evolved and a new substance is formed having new characters. Here, reaction between substance A and substance B leads to form a new substance C. So new substance is a compound.

The density of ice is 0.9167 g/cm³ at 0 °C, whereas water has a density of 0.9998 g/cm³ at the same temperature. The density of ice at its melting point is less than density of water. Ice has less density than water, that is why ice floats  on water.

(1) Mixture is a combination of two or more substances that are not chemically united and do not exist in fixed proportions to each other.
(2) Compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by various physical and chemical methods.
(3) Element is a pure chemical substance consisting of one type of atom.
(4) Atom  a basic unit of matter which takes place in a chemical reaction.

For liquids and solid solutes, increasing the temperature not only increases the amount of solute that will dissolve but also increases the rate at which the solute will dissolve. For gases, the reverse is true. An increase in temperature decreases both solubility and rate of solution.
So, statement A and D correct.
A way to measure solubility is to determine the maximum mass of solute that can be dissolved in 100 grams of solvent at a particular temperature. So, statement B correct.
Sodium chloride, NaCl, is a soluble salt. The solubility of sodium chloride is 36 g/100 mL water at 25°C. So, So, statement C incorrect.

When liquid particles are dispersed phase and gas is dispersing phase, the mixture is known as Liquid Aerosol. For example – fog, clouds, mist, hair spray, etc. Clouds and fogs are example of liquid in gas solution. Cloud is formed by combination of water vapour with dust particles. Fogs contain water vapour and gases.

Brass is a solid solution containing approximately 70% of copper and 30% zinc. So, copper is the solvent whereas Zn is solute. Copper and Zinc forms homogenous mixture as constituent particles are not visible.