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.
0.216g of aluminium compound X react with an excess of water water to produce gas. this gas burn completely in O2 to form H2O and 108cm^3of CO2 only . the volume of CO2 was measured at room temperature and pressure
0.108 / n = 24 / 1
n = 0.0045 mole ( CO2 >>0.0045 mole
0.216 - 0.0045 = 0.2115
so Al = 0.2115 / 27 => 0.0078 mole
C = 0.0045 * 1000 => 4.5 and Al = 0.0078 * 1000 = 7.8
he is a good scientist because he postulated that chemical reactions resulted in the rearrangement of the reacting atoms
Answer:
Carbon is the basic compound for making of molecules in biological systems. IN growth medium, carbon sources are added to provide energy.
Explanation:
Without carbon, there would be no life on earth. Carbon molecules have the ability to form bonds that are stable with a vast number of molecules. It can also form bonds with itself. The proteins, amino acids, DNA, RNA, lipids all contain carbon molecules. Hence, it serves as the basic compound for making molecules of life. In the growth culture media, Carbon is added in the form of carbohydrates like glucose or glutamine as it provides main source of energy.
