Item 21 - A student heated a blue solid which
gave off a gas. When tested, the gas
changed cobalt chloride paper to
pink. Which of the following is a
LIKELY component of the gas?
B.
Carbon dioxide
Hydrogen
Dust particles
Water vapour​

I believe the answer is hydrogen because

Explanation:

Procedure

Dissolve 5 g of hydrated cobalt(II) chloride in 100 cm3 of water (solution is TOXIC).

Soak filter paper in this solution, drain and dry in an oven (set at no more that 100 °C), so that it is a definite blue colour.

The filter paper can be cut into small strips and stored in a desiccator with dry silica gel.

chemical energy is stored in the chemical bonds of atoms and molecules. it can only be seen when it is released in a chemical reaction. when chemical energy is released, the substance from which the energy came is often changed into an entirely different substance.

this chemical reaction releases energy in the form of light and heat. chemical energy is the potential energy stored in the arrangement of atoms within molecules. breaking chemical bonds requires energy, while forming new chemical bonds releases energy.

the atp molecule can store energy in the form of a high energy phosphate bond joining the terminal phosphate group to the rest of the molecule. in this form,energy can be stored at one location, then moved from one part of the cell to another, where it can be released to drive other biochemical reactions.

b is the correct answer

mark me brainliest and hope this