Correct Answer: <span>O and P
Reason:
The nature of bond depends on the electronegativity difference of constituent atoms. If difference in electronegativity of constituent atoms is more, it will result in ionic bonding. Alternatively, if difference in electronegativity of constituent atoms is less, it will prefer covalent bonding. Further, covalently bonded </span><span>elements are most likely to form polyatomic ions.
In present case, electronegativity difference of O and P is minimum. Hence, they </span><span>are most likely to form polyatomic ions.</span>
A light layer of vacuum grease is applied to the rim of the belljar. Water at room temperature is placed inside and the vacuum pump is then used to evacuate the vessel. When the air pressure is reduced to the vapour pressure of water at room temperature the water will begin to boil.
Given :
Number of He atoms, 
atoms.
To Find :
How many grams are their in given number of He atoms.
Solution :
We know, molecular mass of He is 4 g. It means that their are 
atoms in 4 g of He.
Let, number of gram He in 
atoms is x , so :
Therefore, grams of He atoms is 22.58 g .
Sodium is an earth-metal (group one), sliver and platinum are d-block metals.... Thus silicon is the metalloid and that is true because it looks like a metal being shiny blue-gray but it exhibit non-metal characteristics, except the fact that it can conduct electricity in a heated state.
The formula that would represent an ionic compound that is composed of calcium and iodide ions is CaI2
Explanation
Ionic compound CaI₂ is formed when Calcium form cation ( <em>a positively charged ion</em>) by losing 2 electrons while two iodine atoms form anion ( <em>a negatively charged ion</em>) by gaining one electron each.
When writing down formula of ionic compound, the formula of cation is written first followed by anion formula. therefore Ca is written first followed by I.
The numeric subscript 2 after I(iodine) indicate that 2 atoms of iodine are involved in bonding.
