Test: Is Matter Around Us Pure - 1


10 Questions MCQ Test Science & Technology for UPSC CSE | Test: Is Matter Around Us Pure - 1


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Attempt Test: Is Matter Around Us Pure - 1 | 10 questions in 10 minutes | Mock test for Class 9 preparation | Free important questions MCQ to study Science & Technology for UPSC CSE for Class 9 Exam | Download free PDF with solutions
QUESTION: 1

A pure substance/element contains:

Solution:
  • A pure element or compound contains only one substance, with no other substances mixed in.
  • Impure materials may be mixtures of elements, mixtures of compounds, or mixtures of elements and compounds.
QUESTION: 2

The smell of hydrogen sulphide (H2S) gas:

Solution:

Hydrogen sulfide is a flammable, colorless gas with a characteristic odour of rotten eggs. It is commonly known as hydrosulfuric acid, sewer gas, and stink damp. People can smell it at low levels.

QUESTION: 3

Which of the following is not a mixture? 

Solution:

Carbon dioxide is not a mixture since it contain fixed ratio of oxygen and carbon in 2:1, which is a property of compound not a mixture.

QUESTION: 4

 Which of the following is a true solution? 

Solution:

True Solution is a homogeneous mixture of two or more substances in which substance dissolved (solute) in solvent has the particle size of less than 10-9 nm or 1 nm. Simple solution of salt in water is an example of true solution. Particles of true solution cannot be filtered through filter paper and are not visible to naked eye.

QUESTION: 5

Which of the following is a chemical change? 

Solution:

Cooking of food is a chemical change because after cooking, the raw ingredients or the vegetables cannot be regained again in the raw form.

QUESTION: 6

The process of separation of insoluble solids from a liquid is called:

Solution:

Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered: the sand stays behind in the filter paper (it becomes the residue ) the water passes through the filter paper (it becomes the filtrate).

QUESTION: 7

Which of the following has the highest solubility at 313 K? 

Solution:


∴ KNO3 has the highest solubility at 313 K.

QUESTION: 8

An example of a liquid metal and a liquid non-metal is:

Solution:

Mercury is the only liquid metal and bromine is the only liquid non-metal. 

Mercury:

  • Mercury is the only metal that is a liquid at normal temperatures and pressure. 
  • Because of the behavior of the valence electrons, mercury has a low melting point, is an electrical and thermal conductor and doesn't form diatomic mercury molecules in the gas phase

Bromine:

  • Bromine has 35 electrons and with7 electrons in its outer shell it has a valency of 1 so, is very reactive. 
  • But, the electrons are very spread out from the atomic nucleus, hence it behaves like a liquid.
  • It is non-metallic because it is a halogen gas that is liquid at STP.
QUESTION: 9

Alloys are:

Solution:

Alloys are homogeneous mixtures of two or more elements. The elements could be two metals, or a metal and a non-metal.
Example: Brass is an example of a substitution alloy of copper and zinc.

QUESTION: 10

Brass is an example of:

Solution:

Brass is an alloy made up of uniform composition of copper and zinc. It is a homogeneous mixture in which zinc and copper can be varied to create a range of brasses with varying properties.

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