Answer:
ATOMIC number of element A is 3
Explanation:
Atomic number is the same as number of protons of an element.
according to the periodic table, Lithium is the element with 3 protons in its neutral state and it's atomic number is 3.
2. How many moles are contained in 0.800 g of calcium chloride (CaCl2)?
1 answer:
You might be interested in
Hello!
The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.
We have the following data:
mo (initial mass) = 53.3 mg
m (final mass after time T) = ? (in mg)
x (number of periods elapsed) = ?
P (Half-life) = 10.0 minutes
T (Elapsed time for sample reduction) = 25.9 minutes
Let's find the number of periods elapsed (x), let us see:
Now, let's find the final mass (m) of this isotope after the elapsed time, let's see:
I Hope this helps, greetings ... DexteR! =)
Answer:
Highest speed: He
Lowest speed: CO2
Explanation:
The rms speed (average speed) of the molecules/atoms in an ideal gas is given by:
where
R is the gas constant
T is the absolute temperature of the gas
M is the molar mass of the gas, which is the mass of the gas per unit mole
From the equation, we see that at equal temperatures, the speed of the molecules in the gas is inversely proportional to the molar mass: the higher the molar mass, the lower the speed, and vice-versa.
In this problem, we have 5 gases:
(CO2) (O2) (He) (N2) (CH4)
Their molar mass is:
CO2: 44 g/mol
O2: 16 g/mol
He: 4 g/mol
N2: 14 g/mol
CH4: 16 g/mol
The gas with lowest molar mass is Helium (He): therefore, this is the gas with greatest average speed.
The gas with highest molar mass is CO2: therefore, this is the gas with lowest average speed.