If the wavelength of light in an experiment on photoelectric effect is increased, then
(A) the photoelectric emissions will not take place
(B) the photoelectric emission may or may not take place
(C) the stopping potential will increase.
(D) the stopping potential will decrease
Choose the correct answer from the options given below:

At what distance should an object be placed from a convex lens of focal length 15 cm to obtain a real image three times the size of the object?

\( (1/16) \)th of the initial amount of a certain radio-active isotope remains undecayed after two hours. The half life of the isotope would be :

A parallel combination of three resistors takes a current of 7.5 A from a 30 V battery.
If the resistances of two resistors are \( 12 \text{ } \Omega \) and \( 10 \text{ } \Omega \), then the resistance of the third resistor is:

An alpha particle is moving in a magnetic field \( (3\hat{i} + 2\hat{j}) \text{ T} \) with the velocity \( (7 \times 10^5 \hat{i}) \text{ m/s} \). The magnetic force acting on the particle is:

A long solenoid carrying a current produces a magnetic field B along its axis. If the value of current is halved and the number of turns per unit length is doubled then the new value of magnetic field is

A small telescope has an objective lens of focal length 100 cm and an eye-piece of focal length 5 cm. The magnifying power of the telescope when the final image is formed at the least distance of distinct vision will be

If \(5 x+y \leq 100, x+y \leq 60, x \geq 0, y \geq 0\). Then one of the corner points of the feasible region is:

The gene controlling the ABO blood groups in humans is :

A cylindrical wire is stretched to increase its length by 10%. The percentage increase in resistance will be

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

Read the passage carefully and answer the Questions
Carboxylic acids are the earliest organic compounds isolated from nature. These are also known as organic acids but are weaker acids as compared to mineral acids. However, they are more acidic than alcohols and phenols because of greater resonance stabilization of the parent acid and its conjugate base. The acidic strength is determined by the \(K _a\), which is called the acidity constant. The greater the value of \(K _a\), the greater the tendency of the acid to ionize and hence the stronger the acid. The acidic strength of the saturated aliphatic carboxylic acid depends upon the inductive effect and its position with respect to - COOH groups. Electron -donating substituents tend to decrease whereas electron -withdrawing substituents tend to increase the acidic strength. The acidic strength of the aromatic carboxylic acid, on the other hand depends upon both the inductive effect and the resonance effect of the substituents.
p-Nitrobenzoic acid is a stronger acid than benzoic acid because of

Let a pair of dice be thrown and the random variable \(X\) be the sum of the numbers that appear on the two dice.
Match List - I with List - II

X	Probability, \(P ( X )\)
(A) 4	(I) \(\frac{1}{6}\)
(B) 5	(II) \(\frac{5}{36}\)
(C) 6	(III) \(\frac{1}{12}\)
(D) 7	(IV) \(\frac{1}{9}\)

Choose the correct answer from the options given below :