X-rays were produced using cobalt (Z = 27) as target. It was observed that the X-ray spectrum contained a strong Kα line of wavelength 0.1785 nm an a weak Kα line of wavelength 0.1930 nm. Then the weak Kα line is due to an impurity whose atomic number is

In a diatomic molecule, the inter-nuclear separation of the ground and first excited electronic state are the same as shown in the figure. If the molecule is initially in the lowest vibrational state of the ground state, then the absorption spectrum will appear as

A

B

C

D

The odds favouring the event of a person hitting a target are 3 to 5. The odds against the event of another person hitting the target are 3 to 2. If each of them fire once at the target, find the probability that both of them hit the target.

A

1\/20

B

4\/20

C

1\/20

D

3\/20

Dev can hit a target 3 times in 6 shots pawan can hit the target 2 times in 6 shots and Lakhan can hit the target 4 times in 4 shots. What is the probability that at least 2 shots hit the target -

A

$$\frac{{2}}{{3}}$$

B

$$\frac{{1}}{{3}}$$

C

$$\frac{{1}}{{2}}$$

D

None of these

The vibrational spectrum of a molecule exhibits a strong line with P and R branches at a frequency $${\nu _1}$$ and a weaker line at a frequency $${\nu _2}$$ . The frequency $${\nu _3}$$ is not shown up. Its vibrational Raman spectrum shows a strongly polarized line at frequency $${\nu _3}$$ and no feature at $${\nu _1}$$ and $${\nu _2}$$ .
Which of the following statements is correct?

A

The molecule could be linear

B

The molecule lacks a centre of inversion

C

$${\nu _1}$$ arises from a symmetric stretching mode

D

$${\nu _3}$$ arises from a bending mode

অ্যালুমিনিয়াম, হিলিয়াম এবং সিলিকনের পারমাণবিক সংখ্যা যথাক্রমে 13, 2 এবং 14 হলে, Al27+He27→Si27+( ) নিউক্লিয়ার বিক্রিয়াতে অনুপস্থিত কণা কোনটি? (Aluminum has atomic number 13, helium has atomic number 2, and silicon has atomic number 14. In the nuclear reaction the missing particle Al27+He27→Si27+( ) is:)

A

A. an α particle

B

a positron

C

an electron

D

a proton

. অ্যালুমিনিয়াম, হিলিয়াম এবং সিলিকনের পারমাণবিক সংখ্যা যথাক্রমে 13, 2 এবং 14 হলে, Al27+He27→Si27+ নিউক্লিয়ার বিক্রিয়াতে অনুপস্থিত কণা কোনটি ? (Aluminum has atomic number 13, helium has atomic number 2, and silicon has atomic number 14. In the nuclear reaction Al27+He27→Si27+ the missing particle is:)

A

an a particle

B

a positrom

C

an electron

D

a proton

The radiation absorbed by elements of low atomic number is lower than that absorbed by elements of high atomic number. This variation of absorption co-efficient with atomic number can be very well applied to

A

froth floatation

B

ash determination

C

carbonization

D

agglomeration

In a engineering, test, a rocket sled is propelled into a target. If the sled's distance d in meters from the target is given by the fomula d = - 1.5 t2+120, where t is the number of seconds after rocket ignition, then how many seconds have passed since rocket ignition when the sled is 10 meters from the target?

A

2.58

B

8.59

C

8.94

D

9.31

If the wavelength of the first line of the Balmer series in the hydrogen spectrum is $$\lambda $$, then the wavelength of the first line of the Lyman series is

A

$$\frac{{27}}{5}\lambda $$

B

$$\frac{5}{{27}}\lambda $$

C

$$\frac{{32}}{{27}}\lambda $$

D

$$\frac{{27}}{{32}}\lambda $$

Cemented carbide cutting tools are
P. made by casting
Q. made of mainly WC and cobalt
R. made of Fe₃C and cobalt
S. made by liquid phase sintering

A

P, Q

B

Q, R

C

P, R

D

Q, S