Question 17
The subscript 2 is the atomic number for helium and subscript 4 is the mass number for Helium
<u><em>explanation</em></u>
when writing down an isotope of an element the mass number of that isotope is written in upper side of the chemical symbol, while atomic number is written on the lower side.
Since 4 is on upper side it is the mass number of He, while 2 is the atomic number since it is on lower side.
Question 18
The type of radiation emitted when polonium -212 form lead 208 is an alpha particle
<u><em>explanation</em></u>
Alpha decay is a decay in which an atomic nuclei emit an alpha particles and be transformed into different atomic nuclei with a mass number that is reduced by 4
polonium 212 is reduced by 4 to form lead 208 therefore it undergo alpha particle decay.
<h3>
Answer:</h3>
#a. 25.33 kPa
#b. 0.25 atmospheres
<h3>
Explanation:</h3>
- Pressure may be measured using several units which include pascals, atmospheres, mmHg and kilopascals.
- These units of measuring pressure may be converted from one unit to another using a conversion factor.
For example;
1 kPa = 7.5 mmHg
Thus, in our case,
#a. To convert 190 mmHg to kPa
we divide 190 mmHg by 7.5 mmHg
= 190 mmHg ÷ 7.5 mmHg
= 25.33 kPa
Hence, 190 mmHg is equivalent to 25.33 kilopascals
Another conversion factor is;
1 atm = 760 mmHg
Therefore, in our case,
#b. To convert 190 mmHg to atmospheres
we divide 190 mmHg by 760 mmHg
That is; 190 mmHg ÷ 760 mmHg
= 0.25 atm
Thus, 190 mmHg is equivalent to 0.25 atm
Answer:
The correct answer is 0.67 g H₂
Explanation:
Isopropyl alcohol (C₃H₇OH) can decompose to give acetone (C₂H₆OH) and hydrogen gas (H₂) according to the following chemical equation:
C₃H₇OH (g) ⇒ C₂H₆CO(g) + H₂(g)
We can calculate the initial mass of isopropyl alcohol from the density and volume data:
density = m/V = 0.785 g/mL
⇒ m = density x V = 0.785 g/mL x 25.6 mL = 20.096 g C₃H₇OH
According to the chemical equation 1 mol of C₃H₇OH gives 1 mol H₂. The molar mass of C₃H₇OH is:
molar mass C₃H₇OH = (12 g/mol x 3) + (1 g/mol x 7) + 16 g/mol + 1 g/mol = 60 g/mol
molar mass H₂ = 1 g/mol x 2 = 2 g/mol
So, we obtain: 2 g H₂ from 60 g C₃H₇OH. We multiply this stoichiometric ratio (2 g H₂/60 g C₃H₇OH) by the initial mass of C₃H₇OH to obtain the mass of H₂ is formed:
20.096 g C₃H₇OH x (2 g H₂/60 g C₃H₇OH) = 0.6698 g ≅ 0.67 g H₂
<span>entropy = heat energy (q) /Temperature(T)
can u now answer it </span>
Because they could have an explosive reaction and could possibly hurt you
