A. True
They are formed behind an obstacle when the wind blows the sand up to it.
Answer:
\A.
Explanation: Bromine and arsenic have the same atomic radius, which is 115 and Potassium has an atomic radius of 220.
Answer:- Oxygen
Explanations:- Elements of same group(family) forms the bonds in almost similar manner. Oxygen and sulfur are the elements of same group and have equal number of valence electrons. So, they form chemical bonds in similar manner as each one needs two more electrons to complete it's octet.
Hydrogen has one valence electron and so it forms only a one single bond.
Nitrogen has 5 valence electrons and it needs three more electrons to complete it's octet and for this it forms three single bonds or one single and one double bond.
Carbon has 4 valence electrons and needs 4 more electrons to complete it's octet. The number of bonds are different for hydrogen, nitrogen and carbon as compared to sulfur.
So, the only and only correct choice is oxygen.
Answer :
(A) Br₂ (s) : molecular solids
(B) AgCl (s) : ionic solids
(C) S (s) : atomic solids
(D) CH₄ (s) : molecular solids
Explanation :
Molecular solids : It is defined as the solids in which they are held together by covalent forces, dipole interactions as attractive forces etc.
Ionic solids : It is defined as the solids in which the atoms composed with oppositely charged ions.
Atomic solids : It is defined as the solids in which the molecules are held together by covalent forces and also includes pure substance.
(A) Br₂ (s)
It is molecular solids because they are held together by covalent forces.
(B) AgCl (s)
It is ionic solids because in this atoms composed with oppositely charged ions.
(C) S (s)
It is atomic solids because it is a pure substance.
(D) CH₄ (s)
It is molecular solids because they are held together by covalent forces.
The given question is incomplete. The complete question is:
An acidic solution at 25°C will have a hydronium ion concentration ________ and a pH value ________.
![[H_3O^+]](https://tex.z-dn.net/?f=%5BH_3O%5E%2B%5D)
> 
M, pH < 7.00
< , pH < 7.00
< ,, pH > 7.00
> ,, pH > 7.00
Answer: > M, pH < 7.00
Explanation:
pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration.
Acids have pH ranging from 1 to 6.9, bases have pH ranging from 7.1 to 14 and neutral solutions have pH equal to 7.
![pH=-\log [H_3O^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH_3O%5E%2B%5D)
![7=-log[H_3O^+]](https://tex.z-dn.net/?f=7%3D-log%5BH_3O%5E%2B%5D)
![[H_3O^+]=10^{-7}](https://tex.z-dn.net/?f=%5BH_3O%5E%2B%5D%3D10%5E%7B-7%7D)
As pH of acids is less than 7, the hydronium ion concentration is greater than
Thus the correct option is > M, pH < 7.00
