1. Lithium, water, edible salt, chalk, Carbon, Lime, Nitrogen, Potassium, Oxygen, Iodides, Iron, Chlorine, etc are some matters.

(a) Among the mentioned matters in the stem which one is called the Universal
Solvent? – Analyze the cause. 5 marks

Explanation:

Water is called the "universal solvent" because it is capable of dissolving more substances than any other liquidIt is water's chemical composition and physical attributes that make it such an excellent solvent. Water molecules have a polar arrangement of oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) had a negative charge. This allows the water molecule to become attracted to many other different types of molecules. Water can become so heavily attracted to a different compound, like salt (NaCl), that it can disrupt the attractive forces that hold the sodium and chloride in the salt compound together and, thus, dissolve it.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

a) the particles of the chair are strongly held together.