Which of the following compounds will give silver mirror with ammoniacal silver nitrate?

A. Formic acid

B. Formaldehyde

C. Benzaldehyde

D. Acetone

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Total number of stereo isomers possible for the given structure :

Match List I with List II

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The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency '$$A$$' $$\times 10^{12}$$ hertz and that has a radiant intensity in that direction of $$\frac{1}{{ 'B'}}$$, watt per steradian. '$$A$$' and '$$B$$' are respectively