NEET Practice Questions (MCQs) with Answers & Solutions

The context states: 'Thus, the sum of the instantaneous current values over one complete cycle is zero, and the average current is zero.' This is because for every positive value, there is a corresponding negative value.

The table for physical quantities and remarks states: 'rms voltage $V = \frac{V_m}{\sqrt{2}}$, $V_m$ is the amplitude of the ac voltage.' This directly provides the relationship.

The 'POINTS TO PONDER 4.' section states: 'Joule heating is such a property, and there is one ampere of rms value of alternating current in a circuit if the current produces the same average heating effect as one ampere of dc current would produce under the same conditions.'

From 'POINTS TO PONDER 2.', 'The power rating of an element used in ac circuits refers to its average power rating.' From 'POINTS TO PONDER 3.', 'The power consumed in an ac circuit is never negative.' And from the example 7.2 explanation, 'Thus, the average power supplied to an inductor over one complete cycle is zero.' However, Case (iv) under power factor discusses LCR series circuit at resonance: 'At resonance Xc – XL= 0, and φ = 0. Therefore, cos φ = 1 and P = I^2Z = I^2R. That is, maximum power is dissipated in a circuit (through R) at resonance.' Thus, option 4 is incorrect.

The context states: 'The instantaneous power dissipated in the resistor is $p = i^2 R = i_m^2 R \sin^2 (\omega t)$'. This directly provides the formula for instantaneous power.

Normal cells show a property called contact inhibition, by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost this property, leading to uncontrolled division.

Cells sloughed from malignant tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property is called metastasis and is the most feared property of malignant tumors.

Ionising radiations like X-rays and gamma rays, and non-ionising radiations like UV cause DNA damage leading to neoplastic transformation. Chemical carcinogens in tobacco smoke are also identified. Alpha-interferon, however, is a biological response modifier used in cancer treatment to activate the immune system.

Several genes called cellular oncogenes (c-onc) or proto-oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells.

MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.