1.
Option B
2.
Apparatus required: candles, glass Steps: 1. Fix a candle on a table, light it. Let it keep burning. 2. Invert a glass over a burning candle. Observation: In step 1. Candle is burning. In step 2. When glass on, candle goes off. Thus proving that candle needs air to burn. Refer to doc for diagram.
3.
Option C
4.
Apparatus required: 2 balloons, long stick with string tied at center Steps: 1. Fill 2 balloons with equal amount of air. 2. Tie both balloons to each end of string. 3. Now remove air from one of the balloon from one end. Observation: In step 2, stick is horizontal in position. In step 3, we observe that the side of balloon with air filled goes down. Thus proving that air has weight. Refer to doc for diagram.
5.
Option B
6.
Ozone molecules in the atmosphere provide important protection from the ultraviolet rays of the sun. Specifically, these molecules are good at absorbing certain ultraviolet rays that can cause sunburn and skin cancer.
7.
Option B
8.
Option D
9.
Option A
10.
Option A
11.
Option A
12.
Option C
13.
A cotton wool shrinks when dipped in water because air present in cotton wool escapes when dipped into water and water enters.
14.
Option C
15.
Option B
16.
In the Earth's atmosphere, called the stratosphere, there is a fairly high concentration of ozone molecules that are formed when the sun hits oxygen molecules. This part of the atmosphere is called the ozone layer.
17.
Option A
18.
Apparatus required: Glass filled with water, cardboard Steps: 1. Fill the glass completely with water and cover the glass with stiff cardboard. Make sure no air bubbles in water below cardboard. 2. Now press the cardboard with your hand and invert glass and remove hand from cardboard. Observation: Cardboard does not fall even though water tries to push the cardboard. The air outside pushes the cardboard with great force from below. This is air pressure. Refer to doc for diagram.
19.
Layers of atmosphere are as follows- 1. Troposphere- The troposphere is the layer next to the ground or surface of the Earth upto 15Km. It is lower layer of atmosphere. This is where we live and clouds are formed. Around 80% of the mass of the atmosphere is in the troposphere. The troposphere is heated by the surface of the Earth. 2. Stratosphere- The stratosphere extends for the next 15-50 km after the troposphere. The planes fly in this layer. Unlike the troposphere the stratosphere gets its heat by the Ozone Layer absorbing radiation from the sun.
20.
Option A