Chemical Reactions and Equations

4 solved questions from Class 10 Science, each with the full working. Tap any question to see the step-by-step solution.

• 1 State the type of chemical reaction when zinc metal reacts with hydrochloric acid to produce hydrogen gas. easy 1 mark Classification of reactions
• 2 Which of the following is the correctly balanced equation for the reaction of magnesium with oxygen to form magnesium oxide? easy MCQ 1 mark Balancing chemical equations
• 3 When 5.0 g of hydrogen gas reacts with excess oxygen at 25°C, how many grams of water are formed? (Molar mass H_2 = 2\,g mol^-1, O_2 = 32\,g mol^-1, H_2O = 18\,g mol^-1) medium 3 marks Stoichiometry using balanced equations
• 4 A 2.00 L bottle contains oxygen gas at STP. It is used to completely combust methane according to the reaction CH_4 + 2O_2 → CO_2 + 2H_2O. Assuming complete consumption of the oxygen, calculate (a) the volume of methane required, (b) the volume of carbon dioxide produced, both at STP. (Take 1\,mol gas = 22.4\,L at STP.) hard 5 marks Gas volume calculations using stoichiometry