Test: Is Matter Around Us Pure (Hard) - Class 9 MCQ

Smog refers to a combination of smoke and fog involving mixing primary pollutants ground level particles along with ozone.

Sublimation method is used for separating substances which on heating change directly into vapour. Substances like iodine, ammonium chloride, naphthalene sublime on heating.

Here, muddy water, milk and blood real colloidal solutions. True solutions are not Colloids. For example, Urea Is Not a colloid because it's a true solution

Explanation:
When a saturated solution of NaCl is heated, the following changes occur:
1. Increase in Temperature:
- Heating the saturated solution of NaCl increases the temperature of the solution.
2. Solubility of NaCl:
- The solubility of most solid solutes, including NaCl, generally increases with an increase in temperature.
- Therefore, heating the saturated solution of NaCl increases the solubility of the salt.
3. Dissolution of Additional NaCl:
- As the solubility of NaCl increases, more NaCl can dissolve in the solution.
- This allows additional NaCl to dissolve in the heated solution.
4. Unsaturated
- The addition of more solute (NaCl) than what the solution can hold at a given temperature results in an unsaturated solution.
- Therefore, the saturated solution of NaCl becomes unsaturated when heated.
Conclusion:
- The correct answer is B: becomes unsaturated.
- Heating a saturated solution of NaCl increases the solubility of the salt, causing it to become unsaturated.

The solute particle cannot be separated from the mixture by the process filtration. The solute particles do not settle down when left undisturbed, that's why the solutionist table.

Answer:

The correct answer is option A: Solute.

Explanation:
To understand why solute is present in a lesser mountain, let's break down the terms and their definitions:
1. Solute: A solute is a substance that is dissolved in a solvent to form a solution. It is the component that is present in a smaller amount in a solution.
2. Solvent: A solvent is a substance that dissolves the solute to form a solution. It is the component that is present in a larger amount in a solution.
3. Solubility: Solubility is a measure of how well a solute can dissolve in a solvent. It is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure.
4. Aqueous An aqueous solution is a solution in which the solvent is water. It can contain one or more solutes dissolved in water.
In the given statement, it mentions that the solute is present in a lesser amount. Therefore, the correct answer is option A: Solute. The solute is the component that is present in a smaller quantity in a solution, while the solvent is present in a larger quantity.

Compounds may be formed by:
- Decomposition of other compounds: Compounds can be formed by breaking down or decomposing other compounds into their constituent elements. This can occur through processes such as electrolysis, thermal decomposition, or chemical reactions.
- Combination of elements: Compounds can also be formed by combining different elements together. This can occur through various chemical reactions where atoms of different elements bond together to form a new compound.
- Combination of compounds: Compounds can also be formed by combining different compounds together. This can occur through chemical reactions where the existing compounds react with each other to form a new compound.
Examples:
- Decomposition of water (H2O) into hydrogen (H2) and oxygen (O2) through electrolysis.
- Combination of hydrogen gas (H2) and oxygen gas (O2) to form water (H2O) through a combustion reaction.
- Combination of sodium chloride (NaCl) and silver nitrate (AgNO3) to form silver chloride (AgCl) and sodium nitrate (NaNO3) through a double displacement reaction.
Conclusion:
Compounds can be formed through various methods, including the decomposition of other compounds, the combination of elements, and the combination of compounds. These processes play a crucial role in chemical reactions and the formation of new substances.

A glass of iced tea is a heterogeneous mixture as it contains both solid and liquid phases simultaneously.

Simple distillation is a method for separating the solvent from a solution. Every pure substance has its own particular melting point and boiling point. One way to check the purity of the separated liquid is to measure its boiling point. For Example, pure water boils at 100 degrees and contains many dissolved solids, its boiling point will be higher than this.

The liquid air is allowed to warm-up slowly in a fractional distillation column, where gases get separated at different heights depending upon their boiling points. Liquid nitrogen has the boiling point of boils to form liquid nitrogen gas and is collected from the column's upper part.

A mixture is a material system made up of two or more different mixed substances but are not combined chemically. A mixture refers to the physical combination of two or more substances on which the identities are retained and are mixed. Honey is a mixture.

Brass is a solid solution containing 70% copper 30% zinc. Here the copper acts as solvent and zinc as the solvent.

Sugar and water appear clear and transparent since it is a true solution.

Take a pinch of iron filing and a pinch of sulphur powder in a hard glass test tube. Hold it in a test tube holder, heat it on the flame till the contents glow. The reaction between sulphur and iron filings is seen in the test tube, and iron sulphide is formed.

Step-1: Separate iron filings with the help of a magnet.

Step-2: Sublimation of the remaining mixture separates ammonium chloride when solid directly converts to gaseous vapours.

Step-3: Add water to the remaining mixture, stir and filter out sand by filtration.

Step-4: The filtrate can be evaporated to get back sodium chloride.

Ammonium chloride is first separated from the mixture by heating. The technique of sublimation is used, next, from a solution of salt and sand in water. Sand is insoluble in water and can be separated by filtration. The solution now contains only salt and water. Salt can be separated by heating the mixture as the only salt will remain in the dish, and water will be evaporated.

1. Collect samples of sugar, salt, chalk powder and sand.

2. Take four beakers.

3. Fill each one of them about two-third with water.

4. Add a teaspoonful of sugar to the first beaker, salt to the second, chalk powder to the third and sand to the fourth.

5. Stir the contents of each beaker with a spoon/stirrer.

6. Wait for a few minutes and observe what happens to the substances added to the water.

He observed that starch forms a translucent mixture(colloid)

Addition of carbon disulphide to a mixture containing iron filings and sulphur powder, leads to the formation of a clear yellow solution when sulphur powder dissolves in carbon disulphide, on gentle shaking. Iron fillings being insoluble settle in the bottom. These can be separated by filtration.

Sodium chloride(salt) and ammonium chloride are both white in colour. To separate it, you can use the method of sublimation.