Question

Which of the following gas is formed at the electrode connected to the negative terminal of the battery?
A.Nitrogen gas
B.Hydrogen gas
C.Oxygen gas
D.Carbon dioxide gas

Answer 1

We know that the negatively charged ions move towards anode and positively charged ions move towards the cathode. When electric current is passed through acidified water by using carbon electrodes then a chemical reaction takes place to form hydrogen and oxygen gas. Electric circuits are closed-loop or path systems that consist of a network of electrical components through which electrons can pass. This route is constructed with electrical wires and is operated by a battery.

Complete answer: When the electrodes are immersed in water and current is passed through the water, bubbles of oxygen and hydrogen form, according to William Nicholson, a British chemist. He found that on the electrode connected to the negative He found that on the electrode connected to the negative terminal, hydrogen bubbles formed, while on the electrode connected to the positive terminal, oxygen bubbles formed.
Chemical reactions occur in a conducting solution as an electric current passes through it. The chemical effect of electric current is what it is called.Due to the electric current the water decomposes into hydrogen and oxygen ions. This is actually a decomposition reaction caused by passing an electric current through acidified water.
The chemical decomposition produced by passing an electric current through a conducting liquid is called electrolysis. Due to decomposition bubbles of oxygen and hydrogen gas are produced at the two electrodes which are immersed in the solution. Anode is a positively charged electrode through which electrons leave an electrical device and cathode is a negatively charged electrode through which electrons enter an electrical device.
The decomposition reaction is as follow:
$2{{H}_{2}}O\to {{O}_{2}}+4{{H}^{+}}$
$4{{H}^{+}}+4{{e}^{-}}\to 2{{H}_{2}}$
$2{{H}_{2}}O\to {{O}_{2}}+2{{H}_{2}}$
The positively charged ions are known as cations and negatively charged ions are known as cations. So here water decomposes into hydrogen cations and oxygen anions. The hydrogen ions are cations i.e., positively charged so they move towards the cathode as the cathode is a negatively charged electrode. The oxygen ions are anions i.e., negatively charged so they move towards the anode as anode is a positively charged electrode.
Therefore, the correct answer is option B.

Additional information: Chemical reactions occur as an electric current passes through a conducting solution. As a consequence, gas bubbles may form on the electrodes. Metal deposits can be seen on electrodes. It is possible that the color of the solution will change. What solution and electrodes are used will determine the reaction.

Note:
Remember that during the electrolysis process there may be change in colour of solution due to release of ions. During electrolysis of $CuS{{O}_{4}}$ solution the blue colour of solution fades away during electrolysis to light green colour. This is due to exchange of ions. The constituents break down into negative and positive ions as electricity is passed through water combined with various substances. An electric current flows through these ions. The better the conductor of electricity, the more ions there will be.