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What is the protein portion of an enzyme, which becomes catalytically active only when associated with non-protein constituents, called?
The NCERT text defines it as: 'In these instances, the protein portion of the enzymes is called the apoenzyme.'
The enzymatic pathway of substrate (S) transformation into product (P) always goes through:
The NCERT text emphasizes: 'There is thus, an obligatory formation of an ‘ES’ complex. E stands for enzyme. This complex formation is a transient phenomenon.'
Which of the following statements about the photoelectric effect is INCORRECT?
According to the provided text, 'For a frequency $\nu$ of incident radiation, lower than the cut-off frequency $\nu_0$, no photoelectric emission is possible even if the intensity is large.' This directly contradicts option 4.
For a given photosensitive material and frequency of incident radiation (above the threshold frequency), how does the photoelectric current relate to the intensity of incident light?
The text states: 'For a given photosensitive material and frequency of incident radiation (above the threshold frequency), the photoelectric current is directly proportional to the intensity of incident light (Fig. 11.2)'. This means it increases linearly.
Which of the following properties of photoelectrons is independent of the intensity of incident radiation?
The context mentions, 'the maximum kinetic energy of photoelectrons varies linearly with the frequency of incident radiation, but is independent of its intensity.' Also, from Fig 11.3 description, 'the stopping potential remains the same as that for the incident radiation of intensity $I_1$ ... Thus, for a given frequency of the incident radiation, the stopping potential is independent of its intensity.' Since $K_{max} = eV_0$, $K_{max}$ is also independent of intensity.
The threshold frequency ($\nu_0$) for photoelectric emission is defined as the:
The text defines it as: 'This minimum, cut-off frequency $\nu_0$, is called the threshold frequency. It is different for different metals.' And 'Below a certain frequency (threshold frequency) $\nu_0$, characteristic of the metal, no photoelectric emission takes place, no matter how large the intensity may be.'
What is the approximate time lag observed between the incidence of light and the emission of photoelectrons, provided the frequency is above the threshold frequency?
The text explicitly states: 'It is now known that emission starts in a time of the order of $10^{-9}$ s or less.' This indicates the instantaneous nature of the process.
Which of the following metals is stated to be sensitive to visible light for photoelectric emission?
The text mentions: 'However, some alkali metals such as lithium, sodium, potassium, caesium and rubidium were sensitive even to visible light.' Zinc and cadmium are mentioned as responding to ultraviolet light.
According to Einstein's photoelectric equation, the maximum kinetic energy of photoelectrons ($K_{max}$) is given by:
Einstein’s photoelectric equation is given as: '$1/2 m v^2_{max} = V_0 e = h\nu – \phi_0 = h (\nu – \nu_0)$'. Here, $\phi_0$ represents the work function, which is $h\nu_0$.
The stopping potential ($V_0$) depends on:
Point 4 in the summary states: 'The stopping potential ($V_0$) depends on (i) the frequency of incident light, and (ii) the nature of the emitter material. For a given frequency of incident light, it is independent of its intensity.'
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.