Answer:
= 72900 years
Explanation:
- The half-life is the time taken by a radioactive material to decay by half the original amount.
- The half-life of plutonium-239 is 24300 years which means it takes 24300 years to decay by half the original amount.
To calculate the time taken for a mass of 8 kg to decay to 1 kg we use;
New mass = Original mass x (1/2) ^n, where n is the number of half-lives
Therefore;
1 kg = 8 kg × (1/2)^n
1/8 = (1/2)^n
solving for n;
n =3
Therefore;
Time = 3 × 24300 years
= 72900 years
It will, therefore, take 72900 years for 8 kg of plutonium-239 to decay to 1 kg.
Answer:
Without angiosperms, average annual rainfall in the area declined by 300 millimeters. In the eastern Amazon basin, the length of the wet season decreased by nearly 3 months. The extent of the wettest rainforests, which receive more than 100 millimeters of rain per month, shrank by 80%.
Answer:
[Ca²⁺] = 1M
[NO₃⁻] = 2M
Explanation:
Calcium nitrate dissociates in water as follows:
Ca(NO₃)₂ ⇒ Ca²⁺ + 2NO₃⁻
The moles of Ca²⁺ can be found using the molar relationship between Ca(NO₃)₂ and Ca²⁺
(0.100mol Ca(NO₃)₂) (Ca²⁺ /Ca(NO₃)₂) = 0.100 mol Ca²⁺
The concentration of Ca²⁺ is then:
[Ca²⁺] = n/V = (0.100mol)/(100.0mL) x (1000ml)/(1L) = 1M
Similarly, moles of NO₃⁻ can be found using the molar relationship between Ca(NO₃)₂ and NO₃⁻:
(0.100mol Ca(NO₃)₂) (2NO₃⁻/Ca(NO₃)₂) = 0.200 mol NO₃⁻
The concentration of NO₃⁻ is then:
[NO₃⁻] = (0.200mol)/(100.0mL) x (1000ml)/(1L) = 2M
Answer:
54 g
Explanation:
1 mole of water = H2O
mass of 1 mole of H2O= mass of h2 + mass of o
= 2× mass of h +mass of o
= 2×1+16 =18 g
1 mole of water = 18g
3moles of water = 18×3g= 54g
Mass = Density × Volume
= 30.0 mg / mL × 375 mL
= 11250 mg
= 11.25 g
∴ the total mass of insulin in the bottle is 11.25 g (11250 mg)
