Answer:
0.625 g
Explanation:
Given data:
Half life of radon-222 = 3.8 days
Total mass of sample = 10 g
Mass left after 15.2 days = ?
Solution:
Number of half lives = T elapsed / Half life
Number of half lives = 15.2 / 3.8
Number of half lives = 4
At time zero = 10 g
At first half life = 10 g/2 = 5 g
At 2nd half life = 5 g/ 2= 2.5 g
At third half life = 2.5 g/2 = 1.25 g
At 4th half life = 1.25 g/2 = 0.625 g
X4O10
Let molar mass of X be y
molar mass = 4y + 10 x 16 = 4y+160
so, moles = 85.2 / (4y+160)
Moles of oxygen = 10 x [85.2 / (4y+160) ]
Mass of oxygen = 16 x 10 x [85.2 / (4y+160) ]
which is 48.0
so, 48 = 16 x 10 x [85.2 / (4y+160) ]
Solve the equation to get y.
y = 31
Explanation:
Both conduction and convection are both forms of heat transfer from one place to another.
- In conduction, there must be contact between two bodies for the process to take place but in convection, the matter moves to transfer heat.
- Conduction mostly occurs in solid substances whereas convection occurs mostly in fluids.
- Heat transfer in conduction is quite slow compared to convection which is much faster.
Example of conduction is heating of iron pot when cooking
Example of convection is the refrigerating system.
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The answer is (4) taxing the colonies without representation in Parliament
This set off the Revolutionary War, and the slogan "no taxation without representation" became famous.
