Atoms and Molecules Science - Atoms and Molecules

Protons and neutrons clump together to form the __________ of an atom.

Arrange the following according to correct Dalton's symbols. Hydrogen Carbon Oxygen Sulphur:

1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be: 

How many hydrogen atoms are there in a water molecule?

The particle which is formed by the loss of electrons by an atom is called _________. (Cation, Anion, Neutron)

The particle which is formed by the gain of electrons by an atom is called _________. (Anion, Cation, Proton)

In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called ______. (Law of Conservation of Mass, Law of Constant Proportion, Law of Multiple Proportions)

In water, the proportion of oxygen and hydrogen is _________ by mass. (1:8, 2:1, 1:2)

The lightest element is ________. (Hydrogen, Helium, Lithium)

The name of Li₃N is lithium nitrite.

A chloride ion has negative charge because it has more electrons than a neutral atom.

A sodium ion has positive charge because it has more protons than a neutral atom.

One mole of sodium sulphate contains 2 atoms of Na, 1 atom of S, 4 atoms of oxygen.

Calculate the formula unit masses of ZnO, Na₂O, K₂CO₃ , given atomic masses of Zn = 65u, Na = 23u, K = 39u, C = 12u, and O = 16u.

How many atoms are present in a
PO₄ ^3– ion?

How many atoms are present in a
H₂S molecule.

What is meant by the term chemical formula?

Write down the names of compounds represented by the following formulae:
CaCO₃.

Calculate the molecular masses of H₂ , O₂ , Cl₂ , CO₂ , CH₄ , C₂H₆ , C₂H₄ , NH₃ , CH₃OH.

Why is it not possible to see an atom even with the most powerful microscope?

Define the atomic mass unit.

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3g of hydrogen gas?

When 5g of calcium is burnt in 2g of oxygen, then 7g of calcium oxide is produced. What mass of calcium oxide will be produced when 5g of calcium is burnt in 20g of oxygen? Which law of chemical combination will govern your answer?

Give symbol and valency of the following ions. Hydroxide ion, carbonate ion.

Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions (Mass of an electron is 9.1 × 10^-28 g). Which one is heavier?

A silver ornament of mass’m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Calculate the number of sodium ions that are present in 212g of sodium carbonate.

In a reaction, 5.3g of sodium carbonate reacted with 6g of acetic acid. The products were 2.2g of carbon dioxide, 0.9g water and 8.2g of sodium Q acetate. Show that these observations are in agreement with the law of conservation of mass. sodium carbonate + acetic acid → sodium acetate + carbon dioxide + water.

State the law of constant proportions. Give one example to illustrate this law.

State the two important laws of chemical combination. How Dalton’s atomic theory explains the two Laws?

Compute the difference in masses of 10³ moles each of magnesium atoms and magnesium ions. (Mass of an electron =9.1 × 10^-31kg)

Which has more number of atoms?
100g of N₂ or 100g of NH₃