Answer:

<h2>10.5 gram(cm)^-3 is the right answer.</h2>
Answer:
4 hours and 30 minutes
Explanation: because first wave was 1:30:00 and the second is 1:34:30
1:30:00 goes into 1:34:30 4 hours and 30 minutes.
Answer:
0.0305 moles of MgCO₃
Explanation:
In order to solve this problem, we first need to calculate the molecular weight of MgCO₃:
- MgCO₃ MW = Atomic mass Mg + Atomic mass C + (Atomic mass O)*3
- MgCO₃ MW = 24.3 + 12 + 16*3 = 84.3 g/mol
Finally we <u>divide the mass by the molecular weight</u>, to calculate the <em>number of moles</em>:
- 2.57 g MgCO₃ ÷ 84.3 g/mol = 0.0305 moles.
Answer : C
Explanation:
a star produces energy by combining two atoms into one creates a powerful burst of energy
Given :
a.
b.
c.
d.
.
To Find :
Find the most likely vale of x for each one .
Solution :
a .
Because boron have valency of 3 .
So , x = 3 .
b . 
Valency of carbon is 4 .
x = 4 .
c . 
Valency of nitrogen is 3 .
Therefore , x = 3 .
d . 
Now ,we know valency of carbon is 4 and hydrogen is 1 .
Also , two hydrogen are already there .
So , only 2 electrons left to share .
Since , chlorine have valency of 1 .
Therefore , only 2 electrons of chlorine can connect .
x = 2 .
Hence , this is the required solution .