1. Through the formation of a chemical bond between two hydrogen atoms, which of
ID: 880236 • Letter: 1
Question
1. Through the formation of a chemical bond between two hydrogen atoms, which of the following statements is always true?
A.One of the hydrogen atoms is ionized.
B.Energy is released during the formation of the bond.
C.A polar covalent bond is formed.
D.Electrons always are between the nuclei of the atoms.
E.Resonance stabilizes the bond.
2. Which of the following Lewis formulas is incorrect?
A.
B.
C.
D.
E.
3. For which of the following pairs of species is the difference in radius the greatest?
A.K+ and Br–
B.O2– and F–
C.Li+ and I–
D.Na and Mg
E.C and F
4. The following species, P^-3, 37/17Cl^- and 40/20Ca^+, all have the same number of:
A.electrons.
B.neutrons.
C.protons.
D.nucleons.
E.isotopes.
Explanation / Answer
Answer –
1) B and D
We are given the formation of H2 molecule from two hydrogen atom and we know hydrogen can formed sign bond only and since both are H it is not polar bond or polar molecules there is also and both hydrogens are ionized. When bond is formed there is energy released. The bond between H-H is covalent bond , so both the electrons are between the two H
So option B and D are only correct.
2) C
We know the Lewis structure of Cl2 there is single bond between both Cl and three lone pair on each Cl, so first Lewis structure is correct . In the second there is NH3 we know there are 3 single bond between the N and 3 H and one lone pair on N, so there is correct structure for NH3 also. In the third one there is N2, so there are need triple bond between both N with lone pair of each, so there is only single bond between N, so this is the incorrect Lewis structure. The Lewis structure for H2O and CH4 are also correct.
3) D
The difference in the radius between Na and Mg is greater than others, because others are nearly equal or very small difference in the radius, since there is cation and anions. In the las pair C and F, C has 70 pm atomic radius and 50 for F, so there is difference is near 20 pm , but in the Na and Mg it is 30, because Na has 180 pm and Mg has 150 pm ,so answer is D.
4 ) A
The different element or ions have only electrons or maybe neutrons, but not proton are different. The given species are not isotops, since all are different elements. All given species has same number of electrons , means all have 18 electrons.
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