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.
Explanation:
Because when two equal forces are applied from opposite directions, they "eliminate" each other.
The train would go right if a 3N force was only applied in the right direction, and it would go left if the same force was only applied to the left.
If a 3N force was applied to the right and a 2N force to the left, it would equal a 1N force to the right (3-2=1).
But there it's 3-3=0, so in practice the force is 0N. Therefore the train won't move.
Answer:
The higher the frequency, the shorter the wavelength
Explanation:
All light waves move through a vacuum at the same speed, the number of wave crests passing by a given point in one second depends on the wavelength.
You should always do A. form a hypothesis before performing an experiment also the other options cannot happen until after an experiment.
The reaction between the magnesium, Mg, and the hydrochloric acid, HCl is given in the equation below,
Mg + 2HCl --> H2 + MgCl2
The number of moles of HCl that is needed for the reaction is calculated below.
n = (0.4681 g Mg)(1 mol Mg/24.305 g Mg)(2 mol HCl/1 mol Mg)
n = 0.0385 mols HCl
From the given concentration, we calculate for the required volume.
V = 0.0385 mols HCl/(0.650 mols/L)
V = 0.05926 L or 59.26 mL
<em>Answer: 59.26 mL of HCl</em>