Everyday Science

One gram of carbohydrates provides approximately 4.1 kilocalories (kcal) of energy, which is the standard value used in nutrition science.

The core of a lead pencil is made of graphite, which is a form of carbon, not lead. Hence, carbon is the correct element used in pencils.

Alnico is an alloy of aluminium, nickel, and cobalt specifically used for making permanent magnets due to its magnetic properties. The other options are aluminium alloys used for structural or mechanical purposes, not for magnets.

Chromium is a metal commonly used in making alloys, such as stainless steel, to improve hardness and corrosion resistance. Gypsum, granite, and limestone are not used in alloy production.

Air is composed mostly of nitrogen, which makes up about 78% of the Earth's atmosphere by volume, making it the gas present in the maximum amount.

Iron deficiency in the diet leads to anaemia, a condition characterized by a reduced number of red blood cells or hemoglobin, causing fatigue and weakness. The other options are caused by different deficiencies: goitre by iodine deficiency, scurvy by vitamin C deficiency, and rickets by vitamin D deficiency.

A group of elephants is called a 'tower.' While 'herd' and 'mob' can refer to groups of animals, the specific collective noun for elephants is 'tower.'

The volume of carbon dioxide in the air is approximately 0.03%, which corresponds to about 400 parts per million. This is much lower than the other options provided.

Osmium is the heaviest naturally occurring metal with the highest density, heavier than iron, mercury, and nickel. This makes option D the correct answer.

Dialysis is a medical treatment used to perform the function of the kidneys when they fail, by removing waste and excess fluid from the blood. Therefore, it is used in the treatment of kidney failure.