Olympiad Test: Is Matter Around us Pure- 2 - Class 9 MCQ

You can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride) from the mixture through the process of sublimation.

The rusting of iron is a chemical change because it is two substances reacting together to make a new substance. When iron rusts, iron molecules react with oxygen molecules to make a compound called iron oxide.

Chromium does not have magnetic properties so it cannot be separated by magnetic separation.

Question:
A solution contains 50 mL of alcohol mixed with 150 mL of water. Calculate the concentration of this solution.
Explanation:
Given:
Volume of alcohol (solute) = 50 mL
Volume of water (solvent) = 150 mL
To calculate:
Concentration of the solution
Steps to calculate the concentration:
1. Calculate the total volume of the solution by adding the volume of alcohol and water:
Total volume = Volume of alcohol + Volume of water
= 50 mL + 150 mL
= 200 mL
2. Use the formula for concentration:
Concentration = (Volume of solute / Total volume) × 100
3. Substitute the values:
Concentration = (50 mL / 200 mL) × 100
= 0.25 × 100
= 25%
Answer:
The concentration of the solution is 25%.
Note: The concentration is expressed as a percentage, which represents the amount of solute (alcohol) in the solution. In this case, the solution contains 25% alcohol.

Previously we told that, D∝ 1/√M

​Now, M_CO2 =2×16+12=44 g/mol

M_N2O=2×14+16=44 g/mol

∴D_CO2 =D_N2O , as diffusion coefficient of CO₂ and N₂O is equal, CO₂ and N₂O cannot be separated by diffusion method.

Decaying of wood and burning of wood, because there will be a change of chemical composition and wood cannot be restored to its original form. Sawing of wood and hammering of nails into a piece of wood are physical processes where the chemical composition of compounds is not changed.

Solid foam is a colloid in which a gas is dispersed in a solid medium, hence, Bread is an example of solid foam.

Mass by mass percentage of a solution = [(Mass of solute) / (Mass of solution)] X 100

Here, mass of solute ( cuSo₄) = 110g

Mass of solution = 550 g

Therefore mass by mass percentage of solution = (110 X 100) / 550= 20%

Hence, the concentration of the solution is 20%.

Ice and air are homogeneous in nature as their particles are not distinctly visible. A homogeneous mixture has a uniform composition throughout its mass. It has no visible boundaries of separation between its various constituents, e.g., air, sugar solution, brass, etc.

A heterogeneous mixture does not have a uniform composition throughout its mass.It has visible boundaries of separation between its various constituents, e.g., soil, wood, blood etc.

The colloidal solution contains two components called dispersing phase and dispersing medium. An emulsion is a mixture of two liquids that would not normally mix. An emulsion contains tiny particles of one liquid suspended in another. There are two basic types of emulsions: oil-in-water (O/W) and water-in-oil (W/O). Shaving cream is not an emulsion because it is a foam.