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.

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.

The isotopic representation of an atom is:

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:  

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.

In CO compound:

Mass of oxygen = 16 g

Mass of carbon = 12 g

In compound:

Mass of oxygen = 32 g

Mass of carbon = 12 g

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

Hence, the correct answer is Option C.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.