Chemistry
grade 8
i term
questions 1-4 refer to the following:
a) k+ b) b c) c1 d) ti e)i-
1. has 7 electrons at the outer level
2. has the electron configuration of the outer level 2s22p/
3. has the same electron configuration as a argon atom
4. has valency electrons in d- orbitals
5. how many electrons does a
a) 16 b) 17 c) 18 d) 37
oion with a charge of -2 contain?
e) 10
6. what is the percent composition by mass of the element oxygen in the compound h3po4
a) 16% b) 31.6 % c) 50% d) 64% e)75%
7. which of the following is the number of electrons at 3th energy level for 19k
a) 8 b) 6 c)3 d) 2 e) 1
8. what is the atomic number of the element whose electron configuration ends in with 3p4
a) 22 b) 16 c) 28 d) 32 e) 34
C⁰ - 4e = C⁺⁴ |1 С⁰- восстановитель, О₂⁰ - окислитель
CO₂ + C = 2CO C⁺⁴ + 2 e = C⁺² |1
C⁰ - 2e = C⁺² |1
( C⁺⁴ - окислитель, C⁰ - восстановитель)
2CO + O2 = 2CO2
O₂⁰ + 4 e = 2O⁻² |1
C⁺² - 2e = C⁺⁴ |2
С⁺²- восстановитель, О₂⁰ - окислитель
2Mg + CO2 = 2MgO + C
C⁺⁴ + 4 e = C⁰ |1Mg⁰ - 2e = Mg⁺² |2
( C⁺⁴ - окислитель, Mg⁰ - восстановитель)