extra sample paper for class 10 science board exam 2026 – Discussion Forum

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Piyush365

Asked: September 30, 2025In: Class 10 Science

During a laboratory experiment, a student compared the reactivity of aluminium, sodium and lead with dilute hydrochloric acid. He added small pieces of each metal into separate test tube containing HCl and observed: • Aluminium caused the solution to heat up. • Sodium reacted vigorously with flames. • Lead produced Bubbles slowly. (a) Explain the reason for the rise in temperature when aluminium reacts with dilute HCl. (b) Give a reason why the reaction of sodium with dilute HCl is extremely vigorous. (c) State why the reaction of lead with dilute HCl is slow and produces only a few bubbles.

During a laboratory experiment, a student compared the reactivity of aluminium, sodium and lead with dilute hydrochloric acid. He added small pieces of each metal into separate test tube containing HCl and observed: • Aluminium caused the solution to heat up. • Sodium reacted vigorously with flames. • Lead produced Bubbles slowly. (a) Explain the reason for the rise in temperature when aluminium reacts with dilute HCl. (b) Give a reason why the reaction of sodium with dilute HCl is extremely vigorous. (c) State why the reaction of lead with dilute HCl is slow and produces only a few bubbles.

(a) Aluminium reacts with dilute HCl in an exothermic reaction, releasing heat and hydrogen gas, causing the temperature to rise. (b) Sodium reacts vigorously with HCl due to its high reactivity, producing hydrogen gas rapidly with heat. (c) Lead reacts ...