Which statement correctly describes why a compound is a pure substance? a compound is not a pure substance because each of its molecules is made up of the atoms of two or more different elements. a compound is a pure substance because its molecule cannot be broken down into simpler particles by physical means. a compound is not a pure substance because it is not an element, and only elements are pure substances. a compound is a pure substance because it consists of two different elements, which are pure substances.

Option (d) is the correct answer.

Explanation:

When two or more different atoms are chemically bonded together then it results in the formation of a pure substance known as a compound.

A compound contains definite proportions of its constituent atoms, therefore, it is pure in nature. Whereas a mixture does not contain its constituent atoms in definite proportions and hence, it is impure in nature.

Thus, we can conclude that out of the given options the statement, a compound is a pure substance because it consists of two different elements, which are pure substances correctly describes why a compound is a pure substance.

OPTION D IS INCORRECT THE ANSWER IS B

Explanation:

i did the test on edge

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.