2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

This question tests the understanding of how metals react with both bases and acids.

1. Reaction with Base: Zinc is an amphoteric metal that reacts with strong bases like sodium hydroxide ($NaOH$) to liberate hydrogen gas and form a complex salt, sodium zincate ($Na_2ZnO_2$). This reaction requires warming to proceed at a reasonable rate.
2. Testing Gas: Hydrogen gas is insoluble in water, so bubbling it through a soap solution traps the gas in bubbles. Since hydrogen is highly flammable, it burns rapidly with a characteristic 'pop' sound when exposed to a flame.
3. Reaction with Acid: Active metals like zinc displace hydrogen from dilute strong acids to form a metal salt and hydrogen gas:

$$Zn(s) + H_2SO_4(aq) \rightarrow ZnSO_4(aq) + H_2(g)$$

In both cases (reaction with a strong base and reaction with a strong acid), the gas evolved is hydrogen.