Symbols of Elements and Their Valencies

Q.

How can you make a chemical equation more informative

Q. The arrow pointing downwards $(\downarrow )$ along with a product represents a gaseous product, whereas the arrow pointing upwards $(\uparrow )$ represents the precipitate in a reaction.

1. True
2. False

Q.

Write the chemical names of the following compounds:

${\mathrm{K}}_2{\mathrm{SO}}_4$

${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$

${\mathrm{NH}}_4\mathrm{Cl}$

$\mathrm{ZnS}$

${\mathrm{Na}}_{3_{}}\mathrm{N}$

$\mathrm{AgBr}$

Q.

What is the formula for calcium bisulfate?

Q.

The number of valence electrons in $O^{2-}$(Z = 8) ion is

1. 6

2. 4

3. 8

4. 2

Q.

When two atomic orbitals combine they form:

1. Three molecular orbital

2. Four molecular orbital

3. One molecular orbital

4. Two molecular orbital

Q.

An ion is a charged particle that carries a positive or negative charge.

1. True
2. False

Q.

The symbol of carbon is

1. CO

2. Co

3. Ca

4. C

Q.

Write any two limitations of a chemical equation.

Q.

Write the name of the compound ${\mathrm{CuSO}}_4$.

Q. Nesslers reagent is_____________.

1. $K_{2}Hg{I}_4$+$KOH$
2. $K_{2}Hg{I}_4$
3. both of the above
4. none of the above

Q. Write the following reaction in the form of a word equation:

Sodium hydroxide reacts with calcium bromide to form calcium hydroxide and sodium bromide.

In $Ca{Br}_2$​ ​, determine the valency of calcium.

1. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; calcium; 2
2. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; potassium; 2
3. Sodium hydroxide + calcium bromide = Calcium hydroxide + sodium bromide; calcium; 1
4. Sodium hydroxide + calcium bromide $\leftrightarrow$ Calcium hydroxide + sodium bromide; calcium; 2

Q. Which among the given options is a Hypophosphite ion?

1. $H_{2}P{O}_2^{-}$
2. $H_{2}P{O}_3^{-}$
3. $H_{3}P{O}_4$
4. $P{O}_4^{3-}$

Q.

The formula of hydrogen phosphate of a metal is MHPO₄.Give the formula of the Metal Sulphite.

Q.

A word equation of a chemical reaction is a way to describe chemical reactions using the name of substances involved.

1. True

2. False

Q. X is an element with atomic number 14

What is the valency of X?

1. 1
2. 2
3. 3
4. 4

Q.

Which of the following statement is correct with respect to the stability of an atom?

1. None of the given options are correct

2. Fully filled outer orbit

3. Number of protons and electrons are equal

4. Number of protons and neutrons are equal

Q.

What is symbol

Q.

Write the name of the compound ${\mathrm{MgCl}}_2$.

Q.

Write true or false. Correct the false statement.

The IUPAC approves the names and symbols of new elements

1. True
2. False

Q. $A,B$ and $C$ are three elements which undergo chemical changes as shown below:
$A_2{O}_3+2B\to B_2{O}_3+2A$
$3CS{O}_4+2B\to B_2(S{O}_4{)}_3+3C$
$3CO+2A\to A_2{O}_3+3C$
The most reactive and the least reactive element are respectively:

1. $A,B$
2. $B,A$
3. $B,C$
4. $C,B$

Q.

Why is the symbol $\mathrm{S}$‘ for sulphur, but ’$\mathrm{Na}$‘ for sodium and ’$\mathrm{Si}$ for silicon?

Q. Write the following in the form of a word equation:
Sodium hydroxide reacts with calcium bromide to form calcium hydroxide and sodium bromide.In the formula $CaB{r}_2$​ what does Ca stand for and what is its valency?

1. Sodium hydroxide + calcium bromide = Calcium hydroxide + sodium bromide; calcium; 1
2. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; calcium; 2
3. Sodium hydroxide + calcium bromide $\leftrightarrow$ Calcium hydroxide + sodium bromide; calcium; 2
4. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; potassium; 2

Q.

The valencies of aluminium and chlorine in the compound $AlC{l}_3$ are ______ and _____ respectively.

1. 1, 3

2. 3, 1

3. 1, 1

4. 3, 3

Q.

State two pieces of qualitative information conveyed by a symbol Na.

Q. Precipitate formation during chemical reaction is indicated by this arrow

1. $\uparrow$
2. $\leftarrow$
3. $\downarrow$
4. $\to$

Q. Write the following reaction in the form of a word equation:

Sodium hydroxide reacts with calcium bromide to form calcium hydroxide and sodium bromide.

In $Ca{Br}_2$​ ​, determine the valency of calcium.

1. Sodium hydroxide + calcium bromide = calcium hydroxide + sodium bromide
   
   Valency: 1
2. Sodium hydroxide + calcium bromide $\to$ calcium hydroxide + sodium bromide
   
   Valency: 2
3. Sodium hydroxide + calcium bromide $\leftrightarrow$ calcium hydroxide + sodium bromide;
   
   Valency: 2
4. Sodium hydroxide + calcium bromide $\to$ calcium hydroxide + sodium bromide;
   
   Valency: 1

Q.

Write the name of the compound ${\mathrm{K}}_2{\mathrm{SO}}_4$.

Q.

If Z=3 What would be the valency of the element, Also name the element

Q. The valency of calcium in calcium hydroxide is ____.

1. +1
2. +2
3. -1
4. -2