Answer: C

Explanation:

The gas molecules trapped in ice at very low temperature forms solid ice like structure called gas hydrate. Gas hydrates are also called Clathrates. Clathrates are complex chemical structure formed when one types of molecule is enclosed in other types of molecules forming lattice structure. Hence, statement 1 is correct.

In the case of gas hydrates, water molecules form lattice structure (cage-like structure) in which the gas molecules are enclosed. If the gas molecules are methane, then that gas hydrate is called methane hydrate. It is to be noted that methane is main constituent of natural gas. When methane hydrate is heated, it reverts back to water and natural gas. Hence, statement 2 is correct.

Answer: C

Explanation:

Solar energy is the light and heat that comes from the sun, which can be used to generate electricity, heat, and other forms of energy. The sun has been providing energy for billions of years, and people have used the sun's rays for warmth and to dry food for thousands of years. Solar energy is a renewable energy source that comes from the sun and is harnessed using panels and mirrors. Hence, statement 1 is correct.

Solar energy is harnessed through passive techniques like orienting buildings to the sun and selecting materials with favorable thermal properties, while active methods involve photovoltaic systems, concentrated solar power, and solar water heating. Solar energy has many global benefits, including: Increasing countries' energy security, Enhancing sustainability, Reducing pollution and Lowering the costs of mitigating global warming. Hence, statement 2 is correct.

Answer: C

Explanation:

Photovoltaic (PV) energy, also known as solar power, is a renewable energy source that uses sunlight to generate electricity. Hence, statement 1 is correct.

PV devices, also known as solar panels, are made of semiconductor materials that absorb photons (light particles) from sunlight and release electrons to create an electric current. This process is called the photovoltaic effect. Hence, statement 2 is correct.

PV devices are made up of small, non-mechanical cells that are usually less than four human hairs thick. Each cell produces about 1–2 watts of power and is protected by glass and/or plastic to withstand the outdoors for many years. Cells are connected together to form larger power-generating units called panels or modules. Hence, statement 3 is correct.

Answer: C

Explanation:

Biogas is a renewable energy source produced when organic matter breaks down in an oxygen-free environment, a process known as anaerobic digestion. Biogas is made up of methane, carbon dioxide, hydrogen sulfide, siloxanes and moisture. Hence, statement 1 is correct.

Biogas can be used for a variety of purposes, including: Power generation, Co-generation, Heat in buildings, Cooking and heating, and Transport fuel. Biogas is produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, waste water and food waste. Hence, statement 2 is correct.

Answer: D

Explanation:

Biodiesel is a renewable, biodegradable fuel made from vegetable oils, animal fats, or recycled restaurant grease. It's a clean-burning substitute for petroleum diesel that's produced through a process called trans esterification, which converts fats and oils into biodiesel and glycerin.

Biodiesel is made from more than 80% vegetable oil, including soybean and canola oil, and the rest is mostly animal fats. Hence, statement 1 is correct.

In the United States, biodiesel is blended at a rate of 5% or less into almost all the diesel fuel sold. Biodiesel is also used for paint removal. It is non-toxic, but it may be less reliable than official products on the market. Before using biodiesel to remove paint or adhesive residue, test it on a small patch first. Hence, statement 2 is correct.