To obtain a n-type silicon semiconductor, it must be doped with

To get eight images of a single object one should have two plane mirror at an angle of :

In a feedback amplifier, if the feedback voltage is in opposite phase, the gain is less than 1. Then it will:

The colour of the third band of a colour coded carbon resistor of resistance \(2.3 \times 10^2 \Omega\) would be

The metre bridge wire is made of alloys such as nichrome because they have :

From the following, choose the element for impurity atoms with which pure silicon should be doped to make it a p-type semiconductor:

An astronomical telescope uses an objective lens of focal length 30 cm. In normal adjustment, distance between the two lenses is 32 cm. The magnifying power of telescope is:

What is the oxidation number of the metal of \([Co(H_2O)(CN)(ox)_2]^{2-}\) coordination entity?

From the statements given, choose the correct option based on the Arrhenius equation
\(k = Ae^{-E_{a}/RT}\)

For an ammeter, voltmeter and galvanometer having resistances \( R_A, R_V \) and \( R_G \) respectively, the correct relation among these resistances:

What should be the size of an obstacle to observe diffraction?

Question based on the following passage :
P-Block elements are placed in group 13 to 18 in the periodic table. Group 15 is nitrogen family.
Nitrogen can react with hydrogen, oxygen, halogens etc. It shows multiple oxidation states in its various oxides i.e. \(N_2O, N_2O_3, N_2O_5\) etc. Important allotropic forms of phosphorus are white, red and black phosporus. Various compounds of phosphorus are phosphine, \(PCl_3, PCl_5\) and oxoacids of phosphorus. Oxidation states \(+1\) to \(+5\) are seen in various oxoacids of phosphorus. Group 17 elements are collectively known as halogens. Bond dissociation enthalpy of \(F_2\) is smaller than \(Cl_2\).
The gases present in group 18 are chemically unreactive, they form only few compounds. Neil Bartlett (in 1962) observed the reaction of a noble gas. Since then, many noble gas compounds have been synthesised.
The bond angle in \(PH_3\) is less than \(PH_4^+\) due to :

The C-O-H bond angle in alcohols is slightly less than tetrahedral angle \(109^{\circ} 28^{\prime}\) due to: