Which of the following practices related to plastic bags is not advisable?
A Plastic bags must be recycled properly.
B Plastic bags must not be used for storing eatables.
C Household waste should be thrown away in plastic bags.
D Shopkeepers should be discouraged from using plastic bags.
Air pollutants are harmful to living things. Which of the following is/are their harmful effect(s)?
(i) They form acid rain.
(ii) They cause breathing problems in humans.
(iii) They interfere with photosynthesis in plants.
(iv) They result in the depletion of ozone layer.
A (i) only
B (i) and (ii) only
C (i), (ii) and (iii) only
D (i), (ii), (iii) and (iv)
It is because acid rain is caused by sulphur dioxide and nitrogen dioxide. Breathing problems are caused by various kinds of pollutants. Dust particles interfere with photosynthesis in plants. Chloro-fluoro carbons or CFCs result in the depletion of ozone layer.
When a light ray is reflected repeatedly by a set of parallel plane mirrors, the intensity of light rays decreases after some reflections. This is because of
A Poor reflection from mirrors
B Absorption of some amount of light by mirrors
C Dispersion of light when the rays travel through the atmosphere
D Scattering of light by the mirrors.
Mirror never absorve light. I think answer is D
A student removes an ice cube tray from the freezer and places it on a table. The ice
cubes are solid and cold. The student forgets to put the ice cube tray back into the
freezer. After some time, the ice cubes should be
A Liquid and warmer
B Solid and warmer
C Liquid and colder
D Solid and colder.
A IS THE ANSWER
Match the columns and select the correct option.
|Column I||Column II|
|a. Boat||1. Underwater|
|b. Ship||2. Across rivers and lakes|
|c. Ferry||3. Across a river or short sea route|
|d. Submarine||4. Long sea route|
A a-2, b-4, c-3, d-1
B a-2, b-1, c-4, d-3
C a-3, b-2, c-1, d-4
D a-1, b-2, c-3, d-4
The correct answer is A.
The pressure on the tyres of a sedan car is P. The
contact surface of each tyre with the floor is a Find
the new contact surface of each tyre when air is
released from the tyre and the pressure of the car is
reduced to 0.75 P.
A 1.25 A
B 1.33 A
C 1.67 A
D 4.00 A
Did not understand.pls explain
The diagram shows a plotting compass placed above a copper wire when there is no current flowing in the wire. What happens to the compass needle when a large direct current flows from point A to point B?
A The compass needle points towards the right.
B The compass needle points towards the left.
C The compass needle points towards upward.
D The compass needle points toward downward.
Why? please explain this?