Answer:
d. Radon-222
Explanation:
²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Alpha particle is a helium nucleus with mass number 4 and atomic number 2. According to the law of conversation of mass, the sum of the mass number and atomic number must be equal on both side of the reaction.
Since the mass number of Ra is 226 and that of He is 4. The mass number of the unknown element must be 226 - 4 = 222.
Since the atomic number of Ra is 88 and that of He is 2. The atomic number of the unknown element must be 88 - 2 = 86.
Now looking in the periodic table Radon is the only element with atomic number 86.
A 72 kg athlete climbs a rope to a height of 12m. Calculate the increase in gravitational potential energy it has experienced.
Answer:
8467.2J
Explanation:
Given parameters:
Mass of the athlete = 72kg
Height of the climb = 12m
Unknown:
Increase in gravitational potential energy it has experienced = ?
Solution:
Gravitational potential energy is the energy due to the position of a body. It is mathematically expressed as;
Gravitational potential energy = m x g x h
m is the mass
g is the acceleration due to gravity = 9.8m/s²
h is the height
Insert the parameters and solve;
Gravitational potential energy = 72 x 9.8 x 12
GPE = 8467.2J
Answer:
See explanation.
Explanation:
Hello there!
In this case, according to the described chemical reaction, we first write the corresponding equation to obtain:

Thus, we proceed as follows:
Part 1 of 3: here, since the molar mass of silver and copper (II) nitrate are 107.87 and 187.55 g/mol respectively, and the mole ratio of the former to the latter is 2:1, we can set up the following stoichiometric expression:

Part 2 of 3: here, the molar mass of copper is 63.55 g/mol and the mole ratio of silver to copper is 2:1, the mass of the former that was used to start the reaction was:

Part 3 of 3: here, the molar mass of silver nitrate is 169.87 g/mol and their mole ratio 2:2, thus, the mass of initial silver nitrate is:

Best regards!
Answer:
Explanation:
<u>1. Word equation:</u>
- <em>mercury(II) oxide → mercury + oxygen </em>
<u>2. Balanced molecular equation:</u>
<u>3. Mole ratio</u>
Write the ratio of the coefficients of the substances that are object of the problem:

<u>4. Calculate the number of moles of O₂(g)</u>
Use the equation for ideal gases:

<u>5. Calculate the number of moles of HgO</u>

<u>6. Convert to mass</u>
- mass = # moles × molar mass
- molar mass of HgO: 216.591g/mol
- mass = 0.315mol × 216.591g/mol = 68.3g
Answer:
Zinc nitrate gives white ppt. which dissolves in excess ammonium hydroxide and produce a colorless solution whereas lead nitrate gives a chalky white ppt. of lead hydroxide which doesnot dissolve.
Explanation:
Hope this helps :)