The half life of a radioactive nuclide is 20 hours. What fraction of original activity will remain after 80 hours ?

A given p-n junction is forward biased. Which of the following statements is correct?

Visible light of wavelength 600 nm falls normally on a single slit and diffraction pattern is obtained on a screen. It is found that the second diffraction minima is at \( \frac{\pi}{3} \). If the first minimum is obtained at \( \theta_1 \), then \( \theta_1 \) is:
Given: \( \sin 25^\circ = \frac{\sqrt{3}}{4} \)

The Q-factor of a resonant LCR series AC circuit is given by

The wave theory of light can not explain the phenomenon of

To reduce the resonant frequency in an LCR series circuit with a generator.

Choose the correct statments from below:
A. Nuclides with same atomic number but different number of neutrons are called Isotopes.
B. Nuclides with same mass number are known as Isotopes.
C. Nuclides with same number of neutrons are called Isobars.
D. More than 99.9% mass of atom is concentrated in nucleus.
Choose the correct answer from the options given below:

Match List-l with List-II

List-l (Name of amino acid)	List-II (One letter code)
(A) Lysine	(I) W
(B) Tryptophan	(II) Q
(C) Tyrosine	(III) K
(D) Glutamine	(IV) Y

Choose the correct answer from the options given below :

If \(x^2-y^2=1\), then which of the following is correct?
(A) \(\left(x^2-1\right)\left(\frac{d y}{d x}\right)^2=x^2\)
(B) \(\left(x^2-1\right)\left(\frac{d^2 y}{d x^2}\right)^2=x^2\)
(C) \(\left(x^2-1\right)^3\left(\frac{d^2 y}{d x^2}\right)^2=x^2\)
(D) \(\left(x^2-1\right)^3\left(\frac{d^2 y}{d x^2}\right)^2=1\)
Choose the correct answer from the options given below :

Read the passage carefully and answer the questions
Optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis are called carbohydrates. They can be broadly classified as monosaccharides, disaccharides and polysaccharides depending on their behavior towards hydrolysis. They are also classified as reducing or non-reducing sugars. Another class of biomolecules is proteins which are polymers of twenty different amino acids linked by peptide bonds. Amino acids can be classified as acidic, basic or neutral depending on the relative number of amino and carboxyl groups in their molecule. The essential amino acids cannot be synthesized by our body and hence must be provided through diet. Nucleic acids are the polymers of nucleotides which in turn consist of a base, pentose sugar and phosphate. There are two types of nucleic acids namely, DNA and RNA which differ in the composition of sugar and a base
Which of the following is non-reducing sugar?

Which of the following statements are correct:
A. In semiconductor diodes carriers are generated by photo-excitation.
B. When the photo diode is illuminated with light with energy (E) > Energy gap (Eg) of the semiconductor, then electron-holepairs are generated.
C. Photovoltaic devices convert electricity into optical radiation.
D. Photodiode can be used as a photodetector to detect optical signal.
E. Zener diode specification should be taken as per the required output voltage.
Choose the correct answer from the following options given below:

A proton and \(\alpha\)-particle have same kinetic energy. The de-Broglie wavelength ratio \( \frac{\lambda_p}{\lambda_{\alpha}} \) is equal to:

Which of the following bond in DNA strand is broken by the action of restriction enzyme?