Mercury is the only metal that is liquid at normal temperatures.

Therefore, the correct option is (C) Magnesium ribbon on burning in air produces: 'Magnesium oxide, heat and light'.

Alkali metals (lithium, sodium, potassium) are so soft that they can be cut with a knife. The freshly cut surface is a shiny, silver colour, but this tarnishes quickly to a dull grey as the metal reacts with oxygen and water in the air.

1. Which of the following calcium elements is not a component of baking soda?

2. The chemical formula of baking soda is NaHCO3, which is composed of four elements sodium, hydrogen, carbon and oxygen.

3. Baking soda is an alkaline substance used as a leavening agent in baking.

1. Charles's law (also known as volume law) is an experimental gas law.

2. The volume of a gas increases with its absolute temperature and as its absolute temperature decreases its volume also decreases.

3. Charles's law was studied in the year 1787.

1. That class of compounds, which contain a functional group –OH, is called alcohol.

2. Alcohols contain a hydrogen atom and a hydroxyl group (-OH) along with a carbon atom.

3. The hydroxyl group is a polar group, which makes the alcohol soluble in water.

1. Hydrogen matches the properties of the first group and seventh group of the periodic table.

2. Following is some additional information about the properties of hydrogen.

- Hydrogen is a highly flammable gas.

-Hydrogen is a major component of water.

- Hydrogen can be used as fuel.

Hydrogen is used in the chemical industry to make many types of products.

1. In 1845, the German chemist who published a method for the synthesis of 'acetic acid', a natural product containing two carbon atoms, was Hermann Kolbe.

2. He created carbon disulfide with chlorine, and the end result was carbon tetrachloride.