Answer:
a) Cl, 17 protons and 17 electrons
Explanation:
The elements of group 17 are called halogens. These are six elements Fluorine, Chlorine, Bromine, Iodine, Astatine. The atomic number of chlorine is 17. Its means it has 17 protons and 17 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. Thus the atomic mass of chlorine will be 17+18 = 35 amu
Number protons = 17
Number of electrons = 17
Number of neutrons = 18
Properties of Chlorine:
1. it is greenish-yellow irritating gas.
2. its melting point is 172.2 K
3. its boiling point is 238.6 K
4. it is disinfectant and can kill the bacteria.
5. it is also used in manufacturing of paper, paints and textile industries.
The complete table is shown in figure
a) NH3 is polar as the bonds between N and H are polar. Due to asymmetry in the molecule the molecule is polar
The shape of molecule is trigonal pyramidal while its electronic geometry is tetrahedral.
b) CO2: it is a non polar molecule with polar bonds. The molecule becomes non polar as the dipole moment cancel each other. [Dipole moment is a vector quantity]
The shape is linear.
Answer:
d) cut the large sized Cu solid into smaller sized pieces
Explanation:
The aim of the question is to select the right condition for that would increases the rate of the reaction.
a) use a large sized piece of the solid Cu
This option is wrong. Reducing the surface area decreases the reaction rate.
b) lower the initial temperature below 25 °C for the liquid reactant, HNO3
Hugher temperatures leads to faster reactions hence this option is wrong.
c) use a 0.5 M HNO3 instead of 2.0 M HNO3
Higher concentration leads to increased rate of reaction. Hence this option is wrong.
d) cut the large sized Cu solid into smaller sized pieces
This leads to an increased surface area of the reactants, which leads to an increased rate of the reaction. This is the correct option.
The answer is 7. Valence electrons are the electrons in the very last shell, so we need to look at the outer “circle” and count the electrons, or the little black dots. There are 7 in the last shell.
