Science One word answer.

In a PO₄^3-ion, five atoms are present; one of phosphorus and four of oxygen.

In an H₂S molecule, three atoms are present; two of hydrogen and one of sulphur.

The chemical formula of a compound means the symbolic representation of the composition of a compound. A chemical formula for a molecule is represented by the group of symbols of the elements that constitute the molecule, and the number of atoms of each element present in one molecule.

CaCO₃ represents the compound calcium carbonate.

Potassium nitrate

K₂SO₄→ Potassium sulphate.

CaCl₂→ Calcium chloride.

Aluminum sulfate

magnesium hydroxide.

sodium suphide.

aluminium chloride.

Sodium oxide

The postulate which can explain the law of definite proportions is that the relative number and the kinds of atoms are constant in a given compound.

Molar mass of nitric acid, HNO₃ = 1 + 14 + 3 × 16 = 63g.

Molar mass of Hydrochloric acid = Molar mass of H + Molar mass of Cl = 1 + 35.5 = 36.5 g.

Molar mass of phosphorus molecule, P4=4 → 31=124 g.

Molar mass of sulphur molecule, S₈ = 8 × 32 = 256g.

Molar mass of ethyne, C₂H₂ = 2 × 12 + 2 × 1 = 28g.

Potassium sulphate is K2SO₄. Elements present are potassium, sulphur and oxygen.

The elements present in baking powder are sodium, hydrogen, carbon, and oxygen.

Hydrogen bromide is HBr. Elements present are hydrogen and bromine.

Quick lime is CaO. Elements present are calcium and oxygen.

Calcium carbonate → CaCO₃.

Aluminium chloride → AlCl₃.

Copper nitrate → Cu (NO₃)₂.

Calcium oxide → CaO.

The chemical formula for Magnesium chloride is MgCl₂.

Molecular formula of glucose = C₆H₁₂O₆
Molecular mass of glucose = (6 × C) + (12 × H) + (6 × O) = 72 + 12 + 96 = 180u

Mass = 12u

Ionic compound: an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions.

Boron and oxygen:
Boron oxide

Formula: B₂O₃

10^-9 → nano

In chemistry, the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules. The concept of valence was developed in the second half of the 19th century and helped successfully explain the molecular structure of inorganic and organic compounds.

As the valency of element X is 4 and that of Y is 1, so the resulting formula is XY₄.

1 mole of water molecules = 18gm.
0.5 mole of water molecules = 0.5 x 18 =9.0gm.

The formula mass of a substance is defined as the sum of the atomic masses of constituent atoms in an ionic compound. This is generally used for ionic compounds which do not contain discrete molecules, but ions as their constituent units.

The molar mass of calcium hydroxide i.e. Ca(OH)₂ is 40g/mol + 2 × 16g/mol + 2 × 1 g/mol = 74g/mol.

One mole of atoms (6.002 × 10²³ atoms)

Law of conservation of mass was proposed by Antoine Lavoisier.

Oxide of element: As valency of oxygen is -2 and that of element is +2 so, the resulting compound is XO.

Magnesium sulphate: MgSO_4.

Carbon is used as a standard for atomic mass scale.

Molar mass of oxygen = 32g.
So, 32g of oxygen = 1mole.
1g of oxygen = 1/32mole
8g of oxygen = 1/32 × 8
⇒ 1/4 moles
= 0.25 moles
no. of particles (molecules) = 0.25 × 6.02 × 10²³
= 1.5 × 10²³
= 1.5 × 10²³

In chemistry, the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules.

The size of an atom is indicated by its radius.

The law of chemical combination proposed by Proust is well known as the law of constant proportions.

One atomic mass unit is defined as exactly one-twelfth the mass of an atom of carbon-12. Its symbol is 'u'.