Answer:
20 amu
Explanation:
An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
Atomic mass = Number of protons + number of neutrons
Atomic number = Number of electrons or number of protons.
In given question it is stated that atom has 11 electrons and -1 charge it means this atom has 12 electrons in neutral state.
Thus it has 12 protons because number of electrons and protons are always equal.
Atomic mass of given atom:
Atomic mass = Number of protons + number of neutrons
Atomic mass = 12 + 8 = 20 amu
Answer:
D
Explanation:
The amount of energy released or absorbed is equal the product of the mass, the specific heat capacity and the temperature change. The temperature change being the difference between the final and initial temperature.
Q = mc∆T
Q = heat energy (Joules, J) m = mass of a substance (kg) c = specific heat (units J/g∙K)
∆ is a symbol meaning "the change in" ∆T = change in temperature (Kelvins, K)
From the data provided in the question, we can deduce that:
Q = 16.7KJ = 16,700J
m = 225g
c = 1.74J/g.k
For the temperature, let the final temperature be f. This means our ∆T = f - 20
16,700 = 225 * 1.74 * (f - 20)
16700 = 391.5 (f - 20)
f - 20 = 16700/391.5
f - 20 = 42.7
f = 20 + 42.7 = 62.7
Answer:

Explanation:
The pressure, the volume and the temperature of an ideal gas are related to each other by the equation of state:

where
p is the pressure of the gas
V is the volume of the gas
n is the number of moles
R is the gas constant
T is the absolute temperature
For the gas in this problem:
n = 2.00 mol is the number of moles
V = 17.4 L is the gas volume
p = 3.00 atm is the gas pressure
is the absolute temperature
Solving for R, we find the gas constant:

Answer:
1.57 x 10⁷m
Explanation:
Given quantity is;
1.57 x 10¹⁴nm
Now;
1 nm = 10⁻⁹
So, let us convert this given quantity;
1 nm = 10⁻⁹
1.57 x 10¹⁴nm will give 1.57 x 10¹⁴ x 10⁻⁹ = 1.57 x 10⁷m