1-. Because Group 7A elements have 7 electrons in their valence shell, they need 1 more electron to complete the octet. Thus, it is generally true that all Group 7 electrons have an oxidation number of 1-. This also explains why electron affinity is largely the highest for Group 7A and lowest for Group 1A.
Answer:
3.125 grams.
Explanation:
- It is known that the decay of a radioactive isotope isotope obeys first order kinetics.
- Half-life time is the time needed for the reactants to be in its half concentration.
- If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
∵ Thulium-167 has a half life of 9.0 days.
∴ The time is needed to calculate the grams are left after (36.0 days) represents (36.0 days / 9.0 days) = 4.0 half-lives.
50.0 grams → (first half life) 25.0 grams → (second half life) 12.5 grams → (third half life) 6.25 grams → (fourth half life) 3.125 grams.
So, the grams are left after 36.0 days = 3.125 grams.
Answer:
3
Explanation:
The reaction expression is given as:
Al(OH)₃ + HNO₃ → H₂O + Al(NO₃)₃
To solve this problem, let us assign coefficient a,b,c and d to each specie;
aAl(OH)₃ + bHNO₃ → cH₂O + dAl(NO₃)₃
Conserving Al : a = d
O: 3a + 3b = c + 9d
H: 3a + b = 2c
N: b = 3d
let a = 1 , d = 1, b = 3 , c = 3
Multiply through by 3;
a = 1, b = 3, c = 3 and d = 1
Al(OH)₃ + 3HNO₃ → 3H₂O + Al(NO₃)₃