The valence of lead is 4.
Hence the name of the compound is called Lead (IV) oxide.
<h3>Further explanation</h3>
Given
PbO₂ compound
Required
The valence of Pb
Solution
The oxidation number of element O in the compound = -2, except for OF₂ the oxidation state = + 2 and the peroxides (Na₂O₂, BaO₂) the oxidation state = -1 and superoxide, for example KO₂ = -1/2.
The oxidation state in the uncharged compound = 0,
So The oxidation state of Pb :
Pb + 2.(-2) = 0
Pb - 4 = 0
Pb = +4
1. Change in temperature
2. Odour being produced
3. Gas bubbles being formed
4. Solid precipitate is formed
5. Permanent change in colour
6. Light is being produced
Hot sauce, ham and cheese
The answers are as follows:
1. C
An atom is made up of three particles, which are electron, proton and neutron.
The proton and the neutron are located in the central part of the atom, which is called the nucleus while the electrons orbit around the nucleus. The electron is negatively charged, the proton is positively charged and the neutron does not have any charge.
2. C.
To calculate the average atomic mass of the element, divide the percentage abundance by 100 and then multiply the mass and the abundance value together for each element. After this add all the values obtained together.
a. Mass * abundance = 23.9850 * 0.7899 = 18.9457515
b. Mass * abundance = 24.9858 * 0.1 = 2.49858
c. Mass * abundance = 25.9826 * 0.1101 = 2.86068426
Relative atomic mass = 18.9457515 + 2.49858 + 2.86068426 = 24.30.
3. A particle that orbit the nucleus is called AN ELECTRON.
An electron is the negatively charged component of the atom, which orbit round the nucleus of an atom. The number of electrons that are orbiting round the nucleus of a particular atom depends on the atomic number of that atom.
4. C.
If an element has a charge of -1, that means that the element has gained one electron in the course of chemical bonding and has become an anion. Normally, for a neutral element, the number of proton, neutron and electron ought to be the same. But in the situation where an element has gained one electron, the number of electron will increase by 1 while the number of proton and neutron remain the same. That is why 9, 9, 10 written at option C is correct.
5. D.
An isotope is defined as an element, which has two or more forms which differ in the number of neutrons in their nucleus. An isotope is an element which exist in several forms. The major difference between isotopes is the number of neutrons in their nucleus and this neutron number eventually determine their relative atomic mass. Thus two isotopes will have different neutron number and different mass number.
6. B.
In the diagram given, there are five neutrons, four proton and two electrons. The atomic particles that can be used here to determine the correct element are neutrons and protons, this is because they do not participate in chemical bonding therefore there number is always constant. The proton number of four indicates that the element we are searching for is beryllium, because beryllium has four protons and five neutrons in its nucleus.
7. B.
The atomic number of iron is 26 but its mass number is 56. Since its atoms are composed of three different particles, the particles number are as follows: electron = 26, proton = 26 and neutron = 30.
Neutron number = mass number - proton number = 56 - 26 = 30.
In the question we are given, the iron element has undergone a bonding process and it has given away two electrons, to become a cation, that is why it is written as Fe2+. Thus, its electron number will become: 26 - 2 = 24. But this process does not affect the neutron number.
8. D.
Quarks refer to subatomic particles which possess fractional electric charges. They are usually find in the proton and the neutron which are located inside the nucleus of an atom. Quark is not found in electrons.
9. D.
The atomic number of sulfur is 16, that means that, it has 16 electrons, 16 protons and 16 neutrons in its atom at the neutral state. Sulfur has many isotopes, the number of neutrons in the isotopes varies greatly. Note that, the proton number of an atom determines its atomic number.
10. B.
Quarks are sub-atomic particles which are usually find inside the proton an the neutron which are located in the nucleus of an atom. High energy electrons and accelerators are usually used to study this sub particles. The electrons which orbit round the nucleus do not have quarks in their interiors.
