Objects should be cooled before their mass is determined on a sensitive balance because it could damage the balance. Also, because it would give you wrong reading of the mass. Hot objects would warm the air around it. A warm air would expand and would produce convection as it rises causing to give the object a mass that is less than the actual. Another reason would be it would cause instability in the readings, the mass would fluctuate every now and then due to the convection currents around the object. It is always recommended to weigh the masses of objects that are in room temperature.
The answer is B (The second one). I'm not sure though.
The atomic number is the simply the number of protons in the atom. So in the first row with atomic number 2, the number of protons is 2.
If the atom has no charge, which I think you can assume for all of these, the number of electrons is equal to the number of protons. So the number of electrons is also 2.
The number of neutrons (which are the particles with no charge in the nucleus) is simply the mass number minus the atomic number i.e. 4 - 2 = 2.
The isotopic symbol is the symbol which is found on the periodic table of elements. There are 2 numbers associated which each element on the table. The larger is the mass number and the smaller is the atomic number. The atomic number or number of protons is what identifies the element. Looking at the periodic table ( https://sciencenotes.org/wp-content/uploads/2015/01/PeriodicTableOfTheElementsBW.pdf or https://simple.wikipedia.org/wiki/Periodic_table_(big) ), it can be seen that the element on the first row above with an atomic number of 2 is Helium with a symbol He. The number that is included with the name is simply the mass number which is 4 in this case, which tells us that this type of helium has 2 neutrons.
Another type (or isotope) of helium is Helium-3 which has one neutron.
Try the next row and post back if you have trouble with it
Since the angle is West of North, therefore to find for
the westward component (horizontal component) of the vector, we use the sin
function:
sin θ = opposite side / hypotenuse = westward component /
resultant vector
So the westward component (x) is:
x = 85.42 sin 23
<span>x = 33.38 unit</span>
Answer:
300 is the answer
Explanation:
Hope that this answer will help you
