Tag: chemistry

Questions Related to chemistry

Food cans are coated with tin and not with zinc because:

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. zinc is costlier than tin

  2. zinc has a higher melting point than tin

  3. zinc is more reactive than tin

  4. zinc is less reactive than tin

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Correct Option: C
Explanation:

Food cans are coated with tin and not with zinc because zinc is above the tin in reactivity series means more reactive than tin and can react with food elements preserved in it.  

Metal at the top of reactivity series and metal at the bottom of the reactivity series are :

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. potassium and gold respectively

  2. gold and potassium respectively

  3. sodium and silver respectively

  4. silver and sodium respectively

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Correct Option: A
Explanation:

Potassium is the most reactive metal so placed at the top in the reactivity series. Gold is least reactive so, placed at the bottom of reactivity series.

Reaction of hydrochloric acid with zinc oxide to form zinc chloride and water is a neutralization reaction.

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. True

  2. False

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Correct Option: A
Explanation:

An acid neutralizes a base when they react with each other and respective salt and water are formed. Metal oxides are basic in nature. Thus, when an acid reacts with a metal oxide both neutralize each other. In this reaction, respective salt and water are formed.

Acid + Metal Oxide $\rightarrow$ Salt + Water

zinc oxide + hydrochloric acid $\rightarrow$ zinc chloride + water

$ 2HCl+ZnO \rightarrow  ZnCl _2+H _2O $

In the reaction between $Al$ and $Fe _2O _3$, what is the correct final reaction?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Al+Fe _2O _3 \rightarrow Al _3O _2+2Fe$

  2. $2Al+Fe _2O _3 \rightarrow Al _2O _3+2Fe$

  3. $Al+Fe _2O _3 \rightarrow Al _2O _3+Fe _2$

  4. $Al+Fe _2O _3 \rightarrow Al _2O _3+2Fe$

Show answer
Correct Option: B
Explanation:

Al will displace iron from solution.
$\displaystyle  2Al+Fe _2O _3 \rightarrow Al _2O _3+2Fe$

The following elements are listed in order of decreasing reactivity as they appear in the electrochemical series.

      $\displaystyle Na, Ca, Mg, Zn, Fe, H, Cu, Hg, Ag, Au$

Of the following, the element that does NOT react with hydrochloric acid to produce hydrogen gas is _______.

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $\displaystyle Zn$

  2. $\displaystyle Fe$

  3. $\displaystyle Hg$

  4. $\displaystyle Ca$

  5. $\displaystyle Mg$

Show answer
Correct Option: C
Explanation:

Hg lies below hydrogen in the reactivity series. Therefore, Hg cannot replace hydrogen from $HCl$ and hydrogen gas is not released.

An unidentifed metal ($X$) gives the following data in an activity series experiment.
$X(s)+Cr{Cl} _{2}(aq)$- color change and bubbles are produced.
$Sr(s)+XCl(aq)$- no change.
Where should element "$X$" be placed on the activity series?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. Above $Sr$

  2. Above both $Cr$ and $Sr$

  3. Above $Cr$ below $Sr$

  4. Below $Cr$ above $Sr$

Show answer
Correct Option: B
Explanation:

In first reaction, $X(s)+CrCl _2(aq)\longrightarrow \text{ color change }+\text{ Bubbles formed.}$

The reaction occur here, So, $X$ is more reactive than $Cr.$
In second reaction, $Sr+XCl\longrightarrow \text{ No change.}$
This reaction is not possible, because $Sr$ is less reactive than $X.$
So, in both cases, $X$ is more reactive. 
So, $X$ should be placed above $Cr$ and $Sr$ in activity series.

$Li$, $K$, $Ca$, $Na$, $Mg$, $Al$, $Zn$, $Fe$, $Pb$, $Cu$, $Hg$, $Ag$
$I$. The reaction $3Fe(s)+2Al{({NO} _{3})} _{3}(aq)\rightarrow 2Al(s)+3Fe{({NO} _{3})} _{2}(aq)$ will occur.
$II$. Iron is higher on the activity series than aluminum.

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. Statement $I$ is true, Statement $II$ is true and is a correct explanation of the phenomena described in $I$

  2. Statement $I$ is true, Statement $II$ is false

  3. Statement $I$ is false, Statement $II$ is true

  4. Statement $I$ is false, Statement $II$ is false

Show answer
Correct Option: A
Explanation:

By using the reactivity series of metals, one can predict the products of displacement reactions . Each element in the reactivity series can be replaced from a compound by any of the elements above it. For ex: $Mg$ can replace $Zn$ from the solution. 

$Al$ is higher on the activity series than $Fe$.
Therefore $Fe$ can not displace $Al$ from $Al{(NO _3)} _3$
$\therefore 3Fe+2Al{(NO _3)} _3\longrightarrow 2Al+3Fe{(NO _3)} _2$ will not occur.

To what type of reaction does the activity series apply?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. Synthesis

  2. Single replacement

  3. Double replacement

  4. Decomposition

Show answer
Correct Option: B,C
Explanation:

An activity series is a list of substances ranked in order of relative reactivity. For example, magnesium metal can knock hydrogen ions out of solution, so it is considered more reactive than elemental hydrogen.

The following elements are listed in order of decreasing reactivity as they appear in the electrochemical series.
      $\displaystyle Na, Ca, Mg, Zn, Fe, H, Cu, Hg, Ag, Au$

The element that is the best reducing agent is :

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $\displaystyle Na$

  2. $\displaystyle Au$

  3. $\displaystyle H$

  4. $\displaystyle Fe$

  5. $\displaystyle Cu$

Show answer
Correct Option: A
Explanation:

Sodium lies above in the reactivity series. Therefore, it is the best reducing agents. It is a metal and therefore can lose electron so it can oxidize itself and can reduce others easily.

Which metals will displace hydrogen from both water and acids?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Li-Ca$

  2. $Mg-Pb$

  3. $Li-Na$

  4. $Cu-Ag$

Show answer
Correct Option: A,C
Explanation:

In nature, Oxidation occurs more than reduction. carbon, Sulfur, Nitrogen etc. gas converted to their oxides. This is oxidation. But, we never heard that their oxides converting to elements. So, $reduction$ is $less$.