Answer: The correct option is 2.
Explanation: Group 15 elements are Nitrogen, phosphorous, Arsenic, Antimony, Bismuth.
To know whether an element exits as a diatomic molecule or not, we look at the atomicity of an element.
Atomicity is the number of atoms of an element combining to form a molecule.
Atomicity of Nitrogen = 2
Atomicity of Phosphorous = 4
Atomicity of Bismuth = 1
Atomicity of Arsenic = 1
The element having atomicity 2 will exist as a diatomic molecule.
Hence, Nitrogen is a diatomic molecule 
According to the reaction equation:
and by using ICE table:
CN- + H2O ↔ HCN + OH-
initial 0.08 0 0
change -X +X +X
Equ (0.08-X) X X
so from the equilibrium equation, we can get Ka expression
when Ka = [HCN] [OH-]/[CN-]
when Ka = Kw/Kb
= (1 x 10^-14) / (4.9 x 10^-10)
= 2 x 10^-5
So, by substitution:
2 x 10^-5 = X^2 / (0.08 - X)
X= 0.0013
∴ [OH] = X = 0.0013
∴ POH = -㏒[OH]
= -㏒0.0013
= 2.886
∴ PH = 14 - POH
= 14 - 2.886 = 11.11
<span>Kr> Br> As> Se> Ge> Ca> Ga > K </span>
B) The carbon atoms in graphite are arranged in widely spaced layers
Explanation:
Graphite is different from other allotropes of carbon because the carbon atoms in graphite are arranged in widely spaced layers. Graphite and diamond are the two main allotropes of carbon that are closely related.
- Both allotropes forms under extreme temperature and pressure. In geology, they are categorized as derivatives of changed rocks.
- Graphite is different from carbon because its atoms are arranged in widely spaced layers.
- Diamond has a packed and cross-linked structure that makes it rigid and very hard.
Learn more:
diamond brainly.com/question/10515084
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Answer:
No.
Explanation: You cannot change the formulas of individual substances because the chemical formula for a given substance is characteristic of that substance.