| Class: 9 | Science |
| Chapter: 2 | Is Matter Around us pure? |
| Contents: | MCQ Online Test with Answers |
Class 9 Science Chapter 2 MCQ with Answers for 2020-2021
Class 9 Science Chapter 2 MCQ Online tests with solution and explanation. There are about 70 questions in the form of objectives with four choices. These MCQ covers the entire chapter of grade 9 Science NCERT Chapter 2. For the preparation of unit tests or terminal exams, students may use these questions as revision.
Q1
Read the following sentences carefully, and choose the correct one:
[A]. The property which allows the materials to be hammered or beaten into thin sheets without breaking is called malleability.
[B]. The property which allows the metals to be drawn or stretched into thin wires without breaking is called ductility.
[C]. the property due to which non-metals break into pieces on hammering is called brittleness.
[D]. All of the above
Answer: Option D
Explanation:Here, all these statements are correct. Hence your answer will be option [D].
Q2
Anushka is completed her science chapter where she wrote some statements. She wants to know whether the statements are correct or not? Anushka wants to take help from you:
[A]. An element cannot be split up into two or more simpler substances because it is made of only one kind of atoms.
[B]. There are 118 elements known at present, out of which 94 elements, occur in nature while the remaining 24 elements have been prepared artificially.
[C]. 11 elements are gases whereas only two elements mercury and bromine a liquid at room temperature.
[D]. All of the above
Answer: Option D
Explanation:Here, all these statements are correct. Hence your answer will be option [D].
Q3
Which of the following are homogeneous in nature?
[A]. Ice, soil
[B]. Wood, air
[C]. Ice, air
[D]. Soil, air
Answer: Option C
Explanation: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. Example – 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. Example – soil, wood, blood etc.
Q4
On the basis of composition of matter, milk is considered to be :
[A]. A pure substance
[B]. An impure substance
[C]. An element
[D]. A compound
Answer: Option B
Explanation:Milk is considered to be an impure substance as it is an emulsion. Emulsion is a colloid in which minute droplets of one liquid are dispersed in another liquid, which is not miscible with it.
Q5
Recently, in a science class test, you are asked a question where you have to say whether the statements are correct or not?
[A]. The solution made by dissolving solute in organic liquids are called non aqueous solutions.
[B]. The substance which is dissolved in a liquid to make a solution is called solvent.
[C]. The solute particles are also called “dispersed particles” and solvents are also known as “dispersion medium”.
[D]. None of the above.
Answer: Option B
Explanation:The substance which is dissolved in a liquid to make a solution is called solute and the liquid in which solute is dissolved is known as solvent. For example, salt solution is made by dissolving salt in water, so in salt solution “salt” is the solute and water is the “solvent”.
Q6
Rusting of an article made up of iron is called:
[A]. Corrosion and it is a physical as well as chemical change.
[B]. Dissolution and it is a physical change.
[C]. Corrosion and it is a chemical change.
[D]. Dissolution and it is a chemical change.
Answer: Option C
Explanation:Actually, rusting of an article, made up of iron is called corrosion.
Corrosion is a chemical change because rust is a chemical compound (hydrated iron oxide) which is totally different from element iron (Fe).
Physical changes are those changes in which no new substances are formed. The substances do not change their identity and they can be easily returned to their original form by some physical processes. Example – melting of ice, glowing of an electric bulb, breaking of glass tumbler etc.
On the other hand, chemical changes are those changes in which new substances are formed. The substances involved change their identity and they get converted into entirely new substances, which cannot be returned to their original form i.e. burning of paper, rusting of iron, burning of magnesium wire etc.
Note: Dissolution is the process in which a solute is dissolved in a solvent to form solution.
Q7
Priya is writing some statements, choose the incorrect statement and help him:
[A]. A soap solution cannot scatter a beam of light passing through it.
[B]. An emulsion is a colloid in which minute droplets of one liquid are dispersed in another liquid which is not miscible with it.
[C]. The gel is a semi-solid colloid in which there is a continuous network of solid particles dispersed in a liquid.
[D]. An aerosol is a colloid in which a solid or liquid is dispersed in a gas as fog, mist etc.
Answer: Option A
Explanation:A soap solution scatters a beam of light passing through it and renders its path visible, therefore, soap solution is a colloid (or colloidal solution).
Q8
Which of the following statement is or are incorrect?
[A]. A solution in which more quantity of solute can be dissolved without raising its temperature, is called an unsaturated solution.
[B]. A solution in which no more solute can be dissolved at that temperature is called a saturated solution.
[C]. If a saturated solution at a particular temperature is heated to a higher temperature, then it becomes unsaturated.
[D]. None of the above.
Answer: Option D
Explanation: Here, are all the statements are correct. Hence, your answer will be option [D].
Q9
Read the following sentences carefully, and choose the correct one:
[A]. Argon is filled in electric bulbs.
[B]. The various gases of air are separated from one another by the fractional distillation of liquid air.
[C]. Fractional distillation separate the various liquids according to their boiling points, as the more volatile liquid distils over first and the less volatile liquid distils over later.
[D]. All the above.
Answer: Option D
Explanation:Here, are all the statements are correct. Hence, your answer will be option [D].
Q10
Which of the following are physical changes?
[A]. Melting of iron metal, rusting of iron metal, bending of an iron rod.
[B]. Melting of iron metal, rusting of iron metal, drawing a wire of iron metal.
[C]. Melting of iron metal, bending of an iron rod, drawing a wire of iron metal.
[D]. Rusting of iron metal, bending of an iron rod, drawing a wire of iron metal.
Answer: Option C
Explanation:The process in option [B] is a chemical change because rusting causes formation of a new compound. Other statements are examples of physical changes where no new compounds are formed. In the process mentioned in other statements, original form of iron can be obtained back from moulded forms.
What is a Solution?
A solution is a homogeneous mixture of two or more substances.
What are the main constituents of air?
The two main constituents of air are oxygen (21%) and nitrogen (78%).
What is Suspension?
A non-homogeneous systems in which solids are dispersed in liquids, are called suspensions. A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium.
Write down two properties of Colloids?
1. Colloids are big enough to scatter a beam of light passing through it and make its path visible.
2. They do not settle down when left undisturbed, that is, a colloid is quite stable.
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