Question

Neutral atoms contain equal numbers of A protons and electrons. B protons and neutrons. C electrons and neutrons. D protons, electrons, and neutrons. 2. The atomic symbol for beryllium, , indicates that the A mass number is 4. B atomic number is 4. C atomic number is 9. D atomic number is equal to 9 4. 3. The atomic mass of an atom of carbon is 12 amu, and the atomic mass of an atom of oxygen is 16 amu. To produce CO2, 16 g of oxygen combine with 12 g of carbon. To produce CO2, 32 g of oxygen combine with 12 g of carbon. The ratio of the mass of oxygen in CO2 to the mass of oxygen in CO is
A. 8:3.
B. 1:1.
C. 2:1.
D. 1:2.

Answer 1

Answer:

For 1: The correct answer is Option A.

For 2: The correct answer is Option B.

For 3: The correct answer is Option C.

Explanation:

For 1:

Atomic number is defined as the number of electrons or number of protons that are present in a neutral atom. It is represented as Z.

Z = Atomic number = Number of electrons = Number of protons

Mass number is defined as the sum of number of protons and number of neutrons present in an atom. It is represented as A.

A = Mass number = Number of protons + Number of neutrons

Hence, the correct answer is Option A.

• For 2:

The isotopic representation of an atom is: $_Z^A\textrm{X}$

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

We are given:

An isotopic representation of beryllium atom:  $_4^9\textrm{Be}$

Thus, the number '4' represents the atomic number of beryllium, number '9' represents the mass number of beryllium atom.

Hence, the correct answer is Option B.

• For 3:

In CO compound:

Mass of oxygen = 16 g

Mass of carbon = 12 g

In $CO_2$ compound:

Mass of oxygen = 32 g

Mass of carbon = 12 g

Thus, the ratio of mass of oxygen in $CO_2$ and CO is:

$CO_2:CO=32:16=2:1$

Hence, the correct answer is Option C.