Answer:

Explanation:
We already know that the mass number of an atom is the sum of the number of protons and the number of neutrons.
So, the mass number of this isotope is;
Number of protons = 7
Number of neutrons = 8
Mass number = 7 + 8 = 15
Hence, the isotope is;

Answer:
Oiling is done on a regular basis to sewing Machine because in the machine there are lots of machinery parts i.e. wheels and axels, etc. which are in continuous use and they possess so much frictional force between them that wear tear may be observed in those parts.
Hello @Lucysrv18,
How are you doing? In this case, we know that Electromagnetic waves that are visible to the human eye is neither made up of two electromagnetic waves nor three. Therefore B and C is incorrect.
These electromagnetic waves are divided and they are our final two options. For sure, i can say that the wavelengths in a visible electromagnetic wave are not divided into nine, but instead it is divided into 7.
The answer to your question is A.
Thank you,
Darian D.
Answer:
Total pressure at equilibrium is 0.2798atm.
Explanation:
For the reaction:
H₂S(g) ⇄ H₂(g) + S(g)
Kp is defined as:

If initial pressure of H₂S is 0.150 atm, equilibrium pressures are:
H₂S(g): 0.150atm - x
H₂(g): x
S(g): x
Replacing in Kp:

X² = 0.1251 - 0.834X
X² + 0.834X - 0.1251 = 0
Solving for X:
X = -0.964 → False solution: There is no negative pressures
X = 0.1298
Thus, pressures are:
H₂S(g): 0.150atm - 0.1298atm = <em>0.0202atm</em>
H₂(g): <em>0.1298atm</em>
S(g): <em>0.1298atm</em>
Thus, total pressure in the container at equilibrium is:
0.0202atm + 0.1298atm + 0.1298atm = <em>0.2798atm</em>