Boron has two stable isotopes, ¹⁰B (19%) and ¹¹B (81%). The atomic mass that should appear for boron in the periodic table is [CBSE PMT 1990]

Question: Boron has two stable isotopes, ¹⁰B (19%) and ¹¹B (81%). The atomic mass that should appear for boron in the periodic table is [CBSE PMT 1990]

(a) 10.8

(b) 10.2

(c) 11.2

(d) 10.0

Correct Answer: (a) 10.8

More Question

1. The weight of 1 x 10²² molecules of CuSO₄.5H₂O is [IIT 1991]
2. If NA is Avogadro’s number then number of valence electrons in 4.2 g of nitride ions (N^3-)
3. Assuming fully decomposed, the volume of CO₂ released at STP on heating 9.85g of BaCO₃ (Atomic mass of Ba=137) will be [CBSE PMT 2000]
4. The atomic weights of two elements A and B are 40 and 80 respectively. If x g of A contains y atoms, how many atoms are present in 2x g of B
5. Total number of atoms represented by the compound CuSO₄.5H₂O is [BHU 2005]
6. What is the concentration of nitrate ions if equal volumes of 0.1 M AgNO₃ and 0.1 M NaCl are mixed together [CPMT 1983; NCERT 1985]
7. Boron has two stable isotopes, ¹⁰B (19%) and ¹¹B (81%). The atomic mass that should appear for boron in the periodic table is [CBSE PMT 1990]
8. When potassium permanganate is titrated against ferrous ammonium sulphate, the equivalent weight of potassium permanganate is [CPMT 1988]
9. In the reaction 2Na₂S₂O₃ + I → Na₂S₄O₆ + 2NaI, the equivalent weight of Na₂S₂O₃ (mol. wt. = M) is equal to
10. 1 mol of CH₄ contains
11. For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be [MP PET 1996]
12. In chemical scale, the relative mass of the isotopic mixture of oxygen atoms (O¹⁶, O¹⁷, O¹⁸) is assumed to be equal to [Bihar MADT 1981]
13. When 100 ml of 1 M NaOH solution and 10 ml of 10ml of NH₂SO₄ solution are mixed together, the resulting solution will be [DPMT 1982]
14. The sulphate of a metal M contains 9.87% of M. This sulphate is isomorphous with ZnSO₄.7H₂O. The atomic weight of M is [IIT 1991]
15. Sulphur forms the chlorides S₂Cl₂ and SCl₂. The equivalent mass of sulphur in SCl₂ is [EAMCET 1985; Pb. CET 2001]
16. 1 amu is equal to
17. The modern atomic weight scale is based on [MP PMT 2002]
18. Which one of the following properties of an element is not variable [Bihar MADT 1981]
19. Which property of an element is always a whole number [MP PMT 1986]
20. Which one of the following pairs of compounds illustrates the law of multiple proportion [EAMCET 1989]
21. The law of definite proportions is not applicable to nitrogen oxide because [EAMCET 1981]