A student wants to design an experiment to demonstrate a combination reaction using common laboratory chemicals. Which of the following setups best fulfills this purpose while ensuring safety and clear observation?
Mixing iron filings with sulfur powder and heating them in a test tube until a black solid forms
A combination reaction is one in which two or more reactants join to form a single product: A + B → AB.
Heating iron filings with sulphur powder gives a single black solid, iron(II) sulphide: Fe + S → FeS. Two elements combine into one compound, and the colour change (grey + yellow → black) is easy to observe.
Lead(II) nitrate with potassium iodide gives yellow PbI₂ plus KNO₃ — a double displacement (precipitation) reaction, and lead compounds are toxic.
Sodium chloride with silver nitrate gives white AgCl plus NaNO₃ — also a double displacement reaction.
Hydrochloric acid with calcium carbonate gives CaCl₂, water and CO₂ — an acid–carbonate reaction producing several products, not a combination.
Hence, the answer is Mixing iron filings with sulfur powder and heating them in a test tube until a black solid forms.
Similar Questions
Which of the following is a balanced chemical equation for the reaction of sodium hydrogencarbonate with hydrochloric acid?
In the reaction where copper(II) oxide reacts with hydrogen gas to form copper and water, which substance undergoes reduction?
Which of the following reactions best represents a combination reaction?
Which of the following methods is commonly used to prevent rancidity in oils and fats?
Which of the following observations best confirms that carbon dioxide is produced when hydrochloric acid reacts with calcium carbonate?
What are the necessary conditions for corrosion or rusting of iron?
The balanced word equation for the reaction between magnesium carbonate and hydrochloric acid is:
What is the first step in balancing a chemical equation?
What is a common observation when magnesium reacts with air?
'Interconversion of states of matter' and 'burning' are examples of:
Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which of the following statement is correct?
I. Insoluble salt is obtained by precipitation reaction.
II. Addition of oxygen or loss of hydrogen is called oxidation.
