Answer:
After 80 years there will be 3 g of element X remaining
Explanation:
Given;
the half life of element X = 20 year
initial mass of element X = 48 g
a) How much is there after 80 years
0 year --------------------------> 48 g
20 years -----------------------> (48g / 2) = 24 g
40 years ------------------------> 12 g
60 years ------------------------> 6 g
80 years --------------------------> 3 g
Therefore, after 80 years there will be 3 g of element X remaining.
The force involved in the orbiting of the earth is gravity!
The speed of light: 299,782,458 m / s
The speed of sound: 340.29 m / s
Light is faster
Answer:
Option B. N2(g) + 3H2(g) → 2NH3(g)
Explanation:
When nitrogen react with hydrogen, they form a product as shown below:
N2+ H2 → NH3
We need to balance the equation. This is illustrated below:
There are 2 atoms of nitrogen on the left side and 1 atom on the right side. To balance it, put 2 in front of NH3 as shown below:
N2+ H2 → 2NH3
Now, There are a total of 6 atoms of Hydrogen on the right side and 2 atoms on the left side side. This can be balanced by putting 3 in front of H2 as shown below:
N2+ 3H2 → 2NH3
Now we see clearly that the equation is balanced as we have equal numbers of atoms of N and H on both sides of the equation
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