First let's find how much 30Si in nature: 100%-92.2%-4.67%=3.13%
Average M = M(28Si) * 0.922 + M(29Si) * 0.0467 + M(30Si) * 0.0313;
Let's substitute all the values we know:
28.09 = 27.98*0.922 + 28.98*0.0467 +x * 0.0313;
x = 30.03 g/mol
Answer:
Explanation:
The first two are easy:
H2O, H3O+ and OH- all exist in an equilibrium
[H3O+] = [OH-] = 10^-7 M
HCl is a strong acid so 1M of it will disassociate completely
[H3O+] = [Cl-] = 1 M
The third one is also an equilibrium as HNO2 is a weak acid. Ka is given so [HNO2] and [NO2-] can be calculated.
The fourth one is a buffer solution so its pH can be looked up to give the concentrations.
Answer:
Weight is mass times gravity
Explanation:
The mass is the weight gravity is the force of attraction and weight is the power pulled by the gravity or smthn like that
Explanation:
Thus, those metals which remain unaffected by moisture, oxygen and carbon dioxide of the air can occur native or free. In other words, the unreactive metals occur in nature in free state because of their low reactivity towards chemical reagents. ... Metals usually occur in combination with nonmetallic elements.
Answer:
(C) Energy is released when the electron is ejected from the atom.
Explanation:
In the Bohr model of the atom, electrons are arranged in energy levels. The electrons in the lowest energy levels are nearest to the nucleus. An electron may move from a lower to a higher energy level by absorbing energy that is equal to the difference between the energies of the higher and lower energy level.
The potential energy of all electrons inside the atom have negative values and an electron which is infinitely far from the nucleus has an electrostatic potential energy of zero.
Energy is absorbed when an electron is removed from the atom (ionization). Hence the process is highly endothermic. Therefore it is false to say that "Energy is released when the electron is ejected from the atom."
