PH + pOH = 14
pOH=14-8=4
(OH-)=10^-4
It would be any white dwarf star
Answer:
1.31x10⁻³ moles of H₂
Explanation:
This is the equation:
Mg(s) + 2H₂O (g) → Mg(OH)₂ (aq) + H₂(g)
Ratio is 1:1, so 1 mol of Mg is needed to produce 1 mol of H₂
Mass / Molar mass = Mol
0.032 g / 24.3 g/m = 1.31x10⁻³ moles
1.31x10⁻³ moles of H₂(g)
Answer: a) 
b) 
c) 
d) 
Explanation:
General representation of an element is given as:_Z^A\textrm{X}
where,
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
In an atom, when neutrons or protons are lost or gains, it directly affects the mass number of an atom.
Atomic number is defined as the number of protons or number of electrons that are present in an atom.
It is characteristic of a particular element.
Atomic number = Number of electrons = Number of proton
a) Z 74, A 186: 
b) Z 80, A 201: 
c) Z 34, A 76: 
d) Z 94, A 239.: 
<span>STP means standard temperature
and pressure at 0°C (273K) and 1 atm (atmosphere). The density of the unknown
gas is 0.63 gram per liter. The deal gas equation is PV = nRT. The n is the
numer of moles and can be represented as mass of the gas, m, divided by the
molar mass, c. so we have,</span>
PV = nRT
PV = (m/c)RT
Since the density is d = m/V
Pc = (m/V)RT
Pc = dRT
c = drT/P
substitute the values into the equation,
c = [(0.63g/L)(0.08206
L-atm/mol-K)(273K)]/(1atm)
<u>c = 14.11 g/mol</u>