NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT text explicitly lists '1. By dehydration of alcohols' and '2. Williamson synthesis' under '7.6.1 Preparation of Ethers'. It mentions '3. From Grignard reagents' as a method for preparing ALCOHOLS, not ethers (Section 7.4.1 for alcohols). Option 4 is a restatement of Williamson synthesis.

The NCERT states, 'The alkyl group should be unhindered and the temperature be kept low. Otherwise the reaction favours the formation of alkene.' This indicates that higher temperatures promote elimination (alkene formation) over substitution (ether formation).

A side note in the NCERT text mentions, 'Diethyl ether has been used widely as an inhalation anaesthetic. But due to its slow effect and an unpleasant recovery period, it has been replaced, as an anaesthetic, by other compounds.'

According to the NCERT text, 'The process of release of urine is called micturition and the neural mechanisms causing it is called the micturition reflex.' It 'initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.' Therefore, option 4 is incorrect because it states simultaneous contraction of the urethral sphincter, which should be relaxation.

The NCERT text states, 'An adult human excretes, on an average, 1 to 1.5 litres of urine per day.'

The NCERT text mentions, 'The urine formed is a light yellow coloured watery fluid which is slightly acidic (pH-6.0) and has a characteristic odour.'

The NCERT states, 'For example, presence of glucose (Glycosuria) and ketone bodies (Ketonuria) in urine are indicative of diabetes mellitus.'

The NCERT states, 'Though the primary function of sweat is to facilitate a cooling effect on the body surface, it also helps in the removal of some of the wastes mentioned above.' The wastes mentioned are NaCl, small amounts of urea, lactic acid.

The NCERT mentions, 'Other than the kidneys, lungs, liver and skin also help in the elimination of excretory wastes. Our lungs remove large amounts of CO$_2$ (approximately 200mL/minute) and also significant quantities of water every day.'

The NCERT states, 'Sebaceous glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum.' Urea is primarily eliminated by kidneys and in small amounts by sweat glands.