NEET Practice Questions (MCQs) with Answers & Solutions

The cathode reaction is explicitly given as: 'Cathode: $\text{O}_2\text{(g)} + 4 \text{H}^+\text{(aq)} + 4 \text{e}^- \longrightarrow 2\text{H}_2\text{O(l)}$'. Thus, water is the primary product of oxygen reduction. (Refer to the detailed explanation of iron corrosion chemistry).

The context states: 'Corrosion slowly coats the surfaces of metallic objects with oxides or other salts of the metal... It causes enormous damage to buildings, bridges, ships and to all objects made of metals especially that of iron.' By converting the metal into oxides or salts, the original metallic properties (strength, integrity) are lost, leading to damage. (Refer to the introductory paragraph about corrosion damage).

The context explains: 'Electrons released at anodic spot move through the metal and go to another spot on the metal and reduce oxygen in the presence of H+'. (Refer to the detailed explanation of iron corrosion chemistry).

The context mentions fuel cells with respect to efficiency improvements and then states: 'Fuel cells are pollution free and in view of their future importance, a variety of fuel cells have been fabricated and tried.' While efficiency is implied, 'pollution free' is the explicit direct advantage mentioned. (Refer to the paragraph before the 'Corrosion' section).

The text explicitly states: 'The chemistry of corrosion is quite complex but it may be considered essentially as an electrochemical phenomenon. At a particular spot... oxidation takes place and that spot behaves as anode... Electrons released at anodic spot move through the metal and go to another spot on the metal and reduce oxygen... This spot behaves as cathode'. This clearly describes an electrochemical cell with distinct anodic and cathodic reactions and electron flow. The objectives section also mentions 'explain corrosion as an electrochemical process'. (Refer to the 'Corrosion' section and 'Objectives').

The NCERT states, 'whereas in the tissues, where low $pO_2$, high $pCO_2$, high $H^+$ concentration and higher temperature exist, the conditions are favourable for dissociation of oxygen from the oxyhaemoglobin.'

According to the NCERT, 'Binding of oxygen with haemoglobin is primarily related to partial pressure of $O_2$.'

The NCERT defines it as, 'A sigmoid curve is obtained when percentage saturation of haemoglobin with $O_2$ is plotted against the $pO_2$. This curve is called the Oxygen dissociation curve.'

The NCERT states, 'In the alveoli, where there is high $pO_2$, low $pCO_2$, lesser $H^+$ concentration and lower temperature, the factors are all favourable for the formation of oxyhaemoglobin.'

The NCERT mentions, 'Every 100 ml of oxygenated blood can deliver around 5 ml of $O_2$ to the tissues under normal physiological conditions.'