Is Matter Around Us Pure - MCQ Test (22-11-2017) - Class 9 MCQ

The most abundant element in earth’s crust is Oxygen. It is present in earth crust in form of oxide, carbonate etc. of metal.

The density of ice at its melting point is less than density of water. Ice have less density than water, that is why ice float on water.

The emulsifier which stabilizes milk emulsion is called Casein. Casein is found in mammalian milk, making up 80% of the protein in cow milk and between 20% and 45% of the protein in human milk.

22 carrot gold is homogenous mixture of 22 parts gold and 2 parts copper or silver. 22 carrot gold is pure gold and an element.

A substance that can be beaten into thin sheets and drawn into thin wire is both malleable and ductile. Gold is most malleable and ductile element.

Correct Statements about Solubility:
There are four statements given about solubility. Let's analyze each statement to determine which ones are correct.
(A) It increases with an increase in temperature:
- This statement is correct. In general, solubility tends to increase with an increase in temperature. This is because higher temperatures provide more energy for the solute particles to break apart and mix with the solvent particles.
(B) Mass of solute dissolution in 100 units of solvent:
- This statement is correct. Solubility is often expressed as the mass of solute that can dissolve in a given amount of solvent. For example, if the solubility of a substance is 50g/100g of water, it means that 50 grams of the substance can dissolve in 100 grams of water.
(C) Solubility of common salt in water is 46g at 20°C:
- This statement is incorrect. The solubility of common salt (sodium chloride) in water at 20°C is approximately 36g/100g of water, not 46g. The solubility of a substance can vary with different temperatures and conditions.
(D) It decreases with a decrease in temperature:
- This statement is correct. In most cases, solubility decreases with a decrease in temperature. This is because lower temperatures reduce the energy available for solute particles to dissolve in the solvent. However, there are some exceptions to this general trend, such as the solubility of gas solutes, which often increase with a decrease in temperature.
Conclusion:
Based on the analysis, the correct statements about solubility are:
- Statement (A): It increases with an increase in temperature.
- Statement (B): Mass of solute dissolution in 100 units of solvent.
- Statement (D): It decreases with a decrease in temperature.
Therefore, the correct answer is option A: (a), (b), and (d) are correct.

The particle size of suspension is greater than 100 nm. So, particle size of substance ‘P’ present in water will be the suspension.

To separate two miscible liquids from a mixture having boiling point temperature difference of more than 2 degree, fractional distillation is used.

The major constituents of universe are Hydrogen and Helium. They are constituent of Sun, stars and other solar bodies.

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.

An emulsion s a colloidal solution formed by mixing of two immiscible liquids.

The coloured material from flower petals can be separated by chromatography process. Chromatography is used to separate materials present in solution in vary trace amount.

The element that possesses characteristic of both metal and non-metal are called metalloid. Arsenic is the element that has properties of both metal and non-metal.

Brass is a homogenous mixture of 70% of Copper and 30% Zinc by mass. Copper and Zinc forms homogenous mixture as constituent particles are not visible

Scattering of beam of light when passes through a solution is called tyndall effect. Colloidal solution shows the tyndall effect and scatter the beam of light.

NH4Cl is separated from NaCl by heating the solid mixture in a test tube. NH₄Cl being sublime change into vapour which can be collected by cooling it. Nacl remain in test tube.

Hydrogen sulphide gas has the smell of rotten egg.

The mixture in which particles are not distributed evenly and forms separate layer if left undisturbed. The mixture of Albumin and water forms a heterogeneous mixture.

The liquid which contains some suspended particles are called suspension. The size of particle is more than 100nm.

=To separate the components of a mixture of NH₄Cl, common salt and sand, mixture is dissolved in water followed by filtration to separate sand. Evaporation of NH₄Cl and common salt mixture is done to dry it. Sublimation of mixture separate NH₄Clfrom common salt being sublime.

Element and compounds are pure substance. Pure substances are made up of only one kind of particles. Elements are made up of atoms and compounds are made up to molecules.

Mass percent of solution = (mass of solute / mass of solution)×100%(mass of solute / mass of solution)×100%
= (4/4+36)×100%
(4/4+36)×100% = 10%.

The size of particles in colloidal solution ranges from 10⁻⁵cm to 10⁻³cm. less than 10⁻⁵ is true solution and more than 10⁻⁷ is suspension.

Boiling point of water decreases with increase in altitude. At the top of mountain where the atmospheric pressure is less than 1 atm water boils below 100°C.

Radium was discovered by Marie Curie.

Explanation:
To determine the solution of molten copper in brass, we need to identify the correct component or alloy that is mixed with copper in its molten state.
Brass is an alloy that is primarily composed of copper and zinc. It is created by melting copper and adding zinc to it. The molten zinc is then mixed with the molten copper to form brass.
Therefore, the correct answer is option B: molten zinc.
Summary:
Brass is a solution of molten copper in molten zinc.

Air is a mixture, salt solution is a true solution and milk is a colloids having disperse phase of protein and fat in dispersing medium of water and other substance.

Brass is a homogeneous mixture of copper and Zinc. Gun powder is not a powder is a simple mixture of saltpeter, sulfur and charcoal. Air is a mixture of gases.

A combination of common salt and Iron filings is a mixture as there is no chemical reaction between them to form new substance.

A dilute solution of alcohol in water is an example of homogenous mixture. Alcohol and water do not forms a separate boundary if left undisturbed and both are uniformly distributed.