Answer:
-15-12-14=-13
Explanation:
we simplify by opening the bracket
Answer:
Option B is correct.
4
Explanation:
We know that 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.
In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,
Number of neutrons + number of proton
2 + 2 = 4
Thus, option B is correct.
Double replacement i believe
Answer:
Atomic radius of Strontium is 27.38pm
Explanation:
In a face-centered cubic structure, the edge, a, could be obtained using pythagoras theorem knowing the hypotenuse of the unit cell, b, is equal to 4r:
a² + a² = b² = (4r)²
2a² = 16r²
a = √8 r
As edge length of Strontium is 77.43pm:
77.43pm / √8 = r
27.38pm = r
<h3>Atomic radius of Strontium is 27.38pm</h3>
Answer:
the 3rd one (0.01 cm the one selected already)
Explanation:
copper wire isn't excessively big, and it wraps around the pencil because its malleable. I think that the most accurate would be 0.01 cm
