What is the relative formula mass, Mr, of CaCO₃?

(Ar Ca = 40, C = 12, O = 16)

A molecule, Z, contains two atoms of oxygen, six atoms of hydrogen and three of carbon.

What is the formula of Z?

In athletics, banned drugs such as nandrolone have been taken illegally to improve performance.

Nandrolone has the molecular formula C₁₈H₂₆O₂.

What is the relative molecular mass, Mr, of nandrolone?

(Relative atomic mass: H = 1; C = 12; O = 16)

Which relative molecular mass, Mr, is not correct form the molecule given?

(Ar H = 1, C = 12, N = 14, O = 16)

What is the percent composition of hydrogen by mass in C₃H₈?

(Ar C = 12, H = 1)

A compound has the formula CH₃CO₂H.

How should the relative molecular mass, Mr, of the compound be calculated?

(Ar H = 1, C = 12, O = 16)

What is the relative molecular mass (Mr) of HNO₃?

(Ar H = 1, N = 14, O = 16)

Two atoms of magnesium, Mg, react with one molecule of oxygen, O₂.

What is the formula of the product?

A compound contains one atom of calcium, two atoms of hydrogen and two atoms of oxygen.

What is the correct chemical formula of the compound?

The relative formula mass, Mr, of copper(II) sulfate, CuSO₄, is 160.

Which mass of sulfur is present in 320 g of copper(II) sulfate?

(Ar Cu = 64, S = 32, O = 16)

The chemical compositions of two substances, W and X, are given:

W: Na(AlSi₃)O₈

X: Ca(Al₂Si₂)O₈

Which statements are correct?

1) W and X contain the same amount of oxygen.

2) W contains three times as much silicon as X.

3) X contains twice as much aluminium as W.

Nitrogen and hydrogen react together to form ammonia.

N2 + 3 H₂ <----> 2 NH₃

When completely converted, 7 tonnes of nitrogen gives 8.5 tonnes of ammonia.

How much nitrogen will be needed to produce 34 tonnes of ammonia?

Water is formed when 48 g of oxygen combine with 6 g of hydrogen.

What mass of oxygen combines with 2 g of hydrogen?

The equation for the reaction between magnesium and dilute sulfuric acid is shown below:

Mg + H₂SO₄ --> MgSO₄ + H₂

How many mass of magnesium sulfate will be formed if 12 g of magnesium are reacted with sulfuric acid?

(Ar H = 1, O = 16, Mg = 24, S = 32)

Calculate the percentage water of crystallisation in magnesium sulfate crystals, MgSO₄.7H₂O, known as Epsom salt.

(Ar H = 1, O = 16, Mg = 24, S = 32)

It is found that 207 g of lead combined with 32 g of sulfur to form 239 g of lead sulfide.

What is the empirical formula of the compound between lead and sulfur?

(Ar S = 32. Pb = 207)

It is found that 54 g of aluminium forms 150 g of aluminium sulfide.

What is the empirical formula of the compound between aluminium and sulfur?

(Ar Al = 27, S = 32)

What is the volume of 3.5 g of hydrogen gas (H₂) at RTP?

(Ar H = 1)

Given the equation:

MgCO₃(s) + H₂SO₄(aq) ---> MgSO₄(aq) + H₂O(l) + CO₂(g)

Calculate the mass of magnesium carbonate needed to make 6 dm³ of carbon dioxide at RTP?

(Ar Mg = 24)

5.95 g of potassium bromide (KBr) iss dissolved in 400 cm³ of water.

Calculate the molarity of KBr solution?

(Ar K = 39, Br = 80)

What mass of sodium hydroxide (NaOH) is needed to make up 500 cm³ (0.500 dm³) of a 0.500 mol dm^-3 NaOH solution?

(Ar Na = 23, O = 16, H = 1)

What is the approximate total number of atoms contained in 2.00 moles of aluminium?

What is the total number of moles of nitrogen particle contain in a vessel?

The temperature and pressure in STP are ....

An unknown compound consist of 40% Carbon, 6,67% Hydrogen, and the rest is Oxygen.

Determine its empirical formula.

(Ar H = 1, C = 12, O = 16)

Calculate the mass percentage of C in C₆H₁₂O₆.

(Ar H = 1, C = 12, O = 16)

Calculate the percentage purity of Au in a 12-karat gold ring.

2.4 g of magnesium metal is reacted with excess oxygen. At the end of the reaction, 3.0 g of magnesium oxide is formed.

Calculate the percentage yield of the reaction.

(Ar Mg = 24, O = 16)

How many gram of NaOH needed to neutralize 100 mL, 0.05 M H₂SO₄ solution?

(Ar Na = 23, O = 16, H = 1)