For radioactive decay, we can relate current amount, initial amount, decay constant and time using:
N = No x exp(-λt)
Half-life = ln(2)/λ
λ = ln(2) / 5730
N/No = 80% = 0.8
0.8 = exp( -ln(2)/5730 x t)
t = 1844 years
Answer:
Mass of carbon dioxide produced = 52.8 g
Explanation:
Given data:
Mass of carbon react = 14.4 g
Mass of oxygen = 56.5 g
Mass of oxygen left = 18.1 g
Mass of carbon dioxide produced = ?
Solution:
C + O₂ → CO₂
Number of moles of C:
Number of moles = mass/ molar mass
Number of moles = 14.4 g/ 12 g/mol
Number of moles = 1.2 mol
18.1 g of oxygen left it means carbon is limiting reactant.
Now we will compare the moles of C with CO₂.
C : CO₂
1 : 1
1.2 : 1.2
Mass of CO₂:
Mass = number of moles × molar mass
Mass = 1.2 mol × 44 g/mol
Mass = 52.8 g
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Answer:
The specific heat of the alloy 
Explanation:
Mass of an alloy 
= 25 gm
Initial temperature 
= 100°c = 373 K
Mass of water 
= 90 gm
Initial temperature of water 
= 25.32 °c = 298.32 K
Final temperature 
= 27.18 °c = 300.18 K
From energy balance equation
Heat lost by alloy = Heat gain by water
[ - ] = 
( - )
25 × × ( 373 - 300.18 ) = 90 × 4.2 (300.18 - 298.32)
This is the specific heat of the alloy.
Answer:
atoms have no overall charge. this is because they contain equal numbers of positive protons and negative electrons
