Bright Academy
Unit Test-2
STD: IX
Subject: Chemistry
Time:
Part -A (objective type question)
Marks:14
1X3=3mark
1. Identify the heterogeneous mixtures from the following:
(a) Air (b) soda water (c) soap solution (d) brass
(choose the best answer)
2. When a fine beam of light enters in a room through a small hole. This happens due to
what phenomenon?
3 The denser particles are forced t the bottom and the lighter particles stay at the top
when spun rapidly. What is the principle behind this method?
t-B (short answers)
Answers
Answer:
Explanation:
Q1
a) Air
Since at some places we find air to be cleaner while at other places the air might be polluted. Thus at some places there is a higher concentration of pollutants while at others there is a lower concentration. Since the Air is not having same concentration everywhere it is a heterogeneous mixture.
Q2
When a fine bean of light enters a room through a small hole. We are able to see a tiny dust particles as they are reflecting the light that is entering the room. This phenomenon of light being reflected by tiny particles is known as Tyndall Effect while the motion of the particles is known as Brownian Motion.
Q3
The principle is known as Centrifugation in this the liquid is spun rapidly and the denser particles are forced to the bottom while the lighter particles to the top. In this method when the mixture is spun rapidly what happens is that due to the speed the particles experience an additional Centrifugal force which serves as an additional gravity thus forcing denser particles to settle down while the lighter particles to rise.