Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas ?
Hydrogen gas is usually liberated when an acid reacts with a metal.
Take few pieces of zinc granules and add $5\,ml$ of dilute $H_2SO_4$. Shake it and pass the gas produced into a soap solution. The bubbles of the soap solution are formed. These soap bubbles contain hydrogen gas.
$2{H_2}S{O_4}\, + \,Zn\, \to Zn{(S{O_4})_2}\, + \,2{H_2} \uparrow $
We can test the evolved hydrogen gas by its burning with a pop sound when a candle is brought near the soap bubbles.
A milkman adds a very small amount of baking soda to fresh milk.
$(a)$ Why does he shift the $pH$ of the fresh milk from $6$ to slightly alkaline ?
$(b)$ Why does this milk take a long time to set as curd ?
A solution turns red litmus blue, its $pH$ is likely to be
Equal lengths of magnesium ribbons are taken in test tubes $A$ and $B$. Hydrochloric acid $(HCl)$ is added to test tube $A$, while acetic acid $(CH_3COOH)$ is added to test tube $B$. Amount and concentration taken for both the acids are same. In which test tube will the fizzing occur more vigorously and why ?
$10 \,mL$ of a solution of $NaOH$ is found to be completely neutralised by $8 \,mL$ of a given solution of $HCl$. If we take $20 \,mL$ of the same solution of $NaOH$, the amount of $HCl$ solution (the same solution as before) required to neutralise it will be ...... $mL$
Which one of the following types of medicines is used for treating indigestion ?