If we convert 1.25 into grams and round it up the answer will be 427.7
Answer:
13 years
Explanation:
From;
0.693/t1/2 = 2.303/t log (No/N)
Where;
t1/12 = half-life of Cobalt-60 = 5.3 years
t = time taken = the unknown
No = mass of radioactive material originally present = 5.2 g
N = mass of radioactive material at time t = 0.95 g
Substituting values;
0.693/5.3 = 2.303/t log (5.2/0.95)
0.131 = 2.303/t(0.738)
0.131 = 1.6996/t
t = 1.6996/0.131
t = 12.97 years
t = 13 years(to the nearest whole number)
Answer:
The wavelength of the light emitted by a hydrogen atom for the given transition is 2166 nm.
Explanation:
The energy of nth energy levels of the H atom is given as:
Energy of the seventh energy level = 
Energy of the seventh energy level = 
Energy of the light emitted will be equal to the energy difference of the both levels.
Wavelength corresponding to energy E can be calculated by using Planck's equation:
The wavelength of the light emitted by a hydrogen atom for the given transition is 2166 nm.
The answer is 33.33 %
The explanation:
According to the reaction equation:
MgCO3(s) + 2HCl (aq) --> MgCl2(aq) + H20(l) + CO2(g)
we can see that 1 mole of MCO3 will produce → 1 mole of CO2
-Now we need o get number of mole of CO2:
and when we have 0.22 g of CO2, so number of mole = mass / molar mass
moles = 0.22 g / 44 g/mol = 0.005 mole
∴ moles of Mg = moles of CO2 = 0.005 mole
∴ mass of Mg = moles * molar mass
= 0.005 * 84 /mol = 0.42 g
∴ Percent of MgCO3 by mass of Mg = 0.42 g / 1.26 * 100
= 33.33 %
Answer:
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