Q1. Explain the effects of acid rain on: 1. Aquatic life 2. Statues and bridges Solution 1. Acid rain disrupts the reproductive cycle of aquatic species. It also leaches aluminum from the soil into the water, clogging the fish's gills and altering their blood chemistry. As a lake becomes acidified, one species after another disappears. 2. Acids present in the acid rain corrodes metals resulting in weakening of the bridges. Acid rain dissolves marble and stone and hence damages the statues. Q2. What is marble cancer? Solution The corrosion of the marble of monuments due to acids present in acid rain is called marble cancer. Q3. What happens when algae growing in water die? Solution Once the algae die, they serve as food for decomposers like bacteria. A lot of oxygen in the water body gets used up. This results in a decrease in the oxygen level which may kill aquatic organisms. Q4. What is an industrial effluent and what does it contain? Solution...
Q1. Name the first astronaut who landed on moon and when did he land on it. Solution On July 21, 1969 the American astronaut, Neil Armstrong, landed on the moon for the first time. Q2. Do all the stars in the sky move? Explain. Solution No. The Earth rotates from West to East on its axis. Hence, all stars in the sky appear to move from East to West. With reference to the Earth, the Pole star does not appear to move in the sky because it is located above the axis of rotation of the Earth in the north direction. It appears to remain stationary at a point in the sky. Q3. Which star is nearest to earth? What does it provides us? Solution The sun is the nearest star. It is the main source of heat and light for all the planets. Q4. Why do the stars appear to us like point objects? Solution The stars are much bigger than the earth, yet they appear to us like point objects because they are millions of kilometres farther away from the earth. ...