Olympiad Test Level 1: Environment and its Conservation - 2 - Class 4 MCQ

Cow Dung is considered as the chief raw material for bio-gas plants. It is because cow dung has high content of nitrogen and gives high-yield of biogas.

Fossil fuels and metallic minerals come in the category of nonrenewable resource, as they cannot be formed in a short span of time. They were created under high pressure and temperature by decomposing decayed plants and animals, millions of years ago.

Natural resources are classified into 2 categories (renewable and non-renewable). Renewable resources can be replenished either naturally or through some recurring processes. Whereas, non-renewable resources cannot be replenished in a short span of time.

Sunlight produces solar energy. The heat of the sun is harnessed to produce energy. For example, Solar energy is used in Solar cooker for cooking food.

Fossil fuels are remains of organisms which were buried deep under the Earth’s crust and were made of decomposed plants and animals.

Coal is obtained through mining. It is extracted from underground or open-pit mines, where it is found in layers of rock. Mining methods are used to access and extract the coal for use as a fuel source.

Earth’s temperature increases because of global warming. The various human activities like burning of fossil fuels, cutting down of forests, etc. have resulted in increased greenhouse gases. Thereby, affecting Earth’s temperature.

Global warming is primarily caused by air pollution, especially the increase in greenhouse gases like carbon dioxide, methane, and nitrous oxide. These gases trap heat in the Earth's atmosphere, leading to a rise in global temperatures.

Cutting down trees in large numbers is called deforestation, not afforestation. Afforestation means planting more trees to increase forest cover.

Continental regions typically have cold winters. These areas experience extreme temperature differences between summer and winter due to their distance from large bodies of water, which can moderate temperatures. Winters tend to be much colder, while summers can be very hot.

Regular servicing of the bus ensures that the engine runs efficiently, reducing harmful emissions and pollution. The other options do not effectively address pollution control.

Industrial waste causes water pollution as all the waste is dumped in water bodies effecting the marine life. Mining activities cause soil erosion, contamination of underground water, air pollution, etc.

Acid rain is caused by sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) released into the atmosphere, which mix with water vapor. These pollutants come from volcanic eruptions, burning fossil fuels, and smoke from factories.

We breathe in oxygen and breathe out carbon dioxide. Plants breathe in carbon dioxide and breathe out oxygen during the process of photosynthesis.

All the matches are correct:

• A: Running water can carry away topsoil, and embankments can help prevent this.
• B: Strong winds can blow away topsoil, and wind breaks (like trees or shrubs) can reduce this.
• C: Indiscriminate felling of trees leads to soil erosion, and afforestation (planting trees) helps prevent it.