The top of a wave is called the wave crest.
We generally represent an element by its symbol. provided with the atomic number and mass number or atomic mass
Atomic number is the number of protons present in an element. It is constant for an element.
The mass number of element is the sum of number of protons and number of neutrons
The atomic mass is the total mass of all the protons and neutrons present in the element (in its nucleus).
the number of electrons is equal to number of protons in a neutral atom of element.
The mass of electrons is not included in the total atomic mass of element as it is very low.
So here
12 = it is the number of protons = atomic number of element.
The true statements are
The combined mass of protons and neutrons is 24.305
To find the atomic mass, multiply the individual atomic masses with their relative abundances and add them up.
10.012*0.1991 + 11.009*0.8009 = 10.810 amu (5 s.f.)
Element X is Boron.
D is the answer. You're welcome...
You can eliminate A, C, and D almost instantly if you know that engineers are construction workers. The answer is B.