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1. Which of the following atoms has a valency of two?
A. Sodium
B. Magnesium
C. Aluminium
D. Chlorine
2. If an element has electronic configuration 2,8,2, its atomic number is
A. 10
B. 12
C. 14
D. 16
4. Which of the following has the highest number of neutrons?
A. ¹H
B. ²H
C. ³H
D. ⁴He
5. Which statement about isotopes is incorrect?
A. They have same number of protons
B. They have different atomic numbers
C. They have different mass numbers
D. They have same chemical properties
7. A neutral atom of calcium (atomic number 20) has how many electrons in the L shell?
A. 2
B. 8
C. 10
D. 18
8. If an atom has 3 shells completely filled, what will be its total number of electrons?
A. 10
B. 18
C. 28
D. 32
9. The atom of an element X has 6 protons and 8 neutrons.The symbol of the element is
A. ¹⁴₆X
B. ⁶₁₄X
C. ¹²₆X
D. ⁸₆X
10. Which element forms an ion with configuration 2,8?
A. Sodium
B. Neon
C. Oxygen
D. Chlorine
12. The number of nucleons in an atom with atomic number 17 and mass number 35 is
A. 17
B. 18
C. 35
D. 52
13. Which of the following pairs represents isobars?
A. ¹⁴₆C and ¹⁴₇N
B. ²₁H and ³₁H
C. ³⁵₁₇Cl and ³⁷₁₇Cl
D. ¹²₆C and ¹⁴₆C
14. How many electrons can be present in the M shell?
A. 8
B. 18
C. 32
D. 2
15. Which statement correctly describes Rutherford’s model?
A. Positive charge spread evenly
B. Electrons embedded in sphere
C. Most mass concentrated in tiny nucleus
D. Electrons stationary inside nucleus
16. The major limitation of Rutherford’s model was that it could not explain
A. Position of electrons
B. Stability of atom
C. Existence of nucleus
D. Mass of atom
17. If number of protons = number of electrons = 8, the atom is
A. Neutral
B. Positively charged
C. Negatively charged
D. Unstable
18. What will be the mass number of an atom with 11 protons and 12 neutrons?
A. 11
B. 12
C. 23
D. 24
19. How many neutrons are present in ¹⁴₆C?
A. 6
B. 7
C. 8
D. 9
20. The isotope of uranium used in nuclear reactors is
A. ²³⁸₉₂U
B. ²³⁵₉₂U
C. ²³²₉₀Th
D. ²³⁹₉₄Pu
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