Answer: the mass number of the daugther atom is 232,
Explanation:
1) Alpha (α) decay is a nuclear reaction in which a nucleus (parent's nucleus) emits an alpha (α) particle and leads to a different atom (daughter atom).
2) The alpha (α) particle is a nucleus of helium atom, i,e, a nucleus with two protons and two neutrons. The symbol used for the α particles is <em>⁴₂He</em>, where the superscript 4 indicates the mass number (2 protons + 2 neutrons = mass number 4), and the subscript 2 indicates the atomic number (number of protons).
3) Then, to determine the mass number of the daughter atom you just need to do a mass number balance:
mass number of the parent atom = mass number of the daugther atom + mass number of the α particle.
The mass number of the radioactive (parent) atom is 90 protons + 142 neutrons = 232.
∴ 232 = x + 4 ⇒ x = 232 - 4 = 228 ← answer.
The full equation may help you to have a wider vision of the problem:
²³²₉₀ X → ⁴₂ He + ²²⁸₈₈ Y
Note this:
- 232 = 4 + 228 (this is a mass number balance)
- 90 = 2 + 88 (this is an atomic number balance)
- X is the parent atom, and Y is the daughter atom
- You can use a periodic table to determine the identity of the unknown atoms (using the atomic numbers).
The answer is (4) Add enough solvent to 30.0 g of solute to make 1.0 L solution. The molarity is calculated using volume of the solution. When solute dissolving, the total volume will change. So the final volume of solution need to be 1.0 L.
Answer:
What mass (g) of barium iodide is contained in 188 mL of a barium iodide solution that has an iodide ion concentration of 0.532 M?
A) 19.6
B) 39.1
C) 19,600
D) 39,100
E) 276
The correct answer to the question is
B) 39.1 grams
Explanation:
To solve the question
The molarity ratio is given by
188 ml of 0.532 M solution of iodide.
Therefore we have number of moles = 0.188 × 0.532 M = 0.100016 Moles
To find the mass, we note that the Number of moles = 
from which we have
Mass = Number of moles × molar mass
Where the molar mass of Barium Iodide = 391.136 g/mol
= 0.100016 moles ×391.136 g/mol = 39.12 g
<span>The mass (in grams) of 8.45 x 10^23 molecules of dextrose is 252.798g
Working:
Mw. dextrose is 180.16 g/mol
therefore 180.16 grams dextrose = 1 mole
therefore 180.16 grams dextrose= 6.022x10^23 molecules (Avogadro's number)
We have 8.45 x 10^23 molecules of dextrose.
Therefore, (180.16 divided by 6.022x10^23) times 8.45x10^23
gives the mass (in grams) of 8.45 x 10^23 molecules of dextrose;
252.798.</span>
Thermal energy will flow from an object high temperature to an object of low one. In this case, the thermal energy will flow from object B to object A.
