Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

Multiple choice chemistry substances in common use preparation, properties and uses of baking soda chemical from common salt compounds of carbon

$NaHCO _{3}$ can be used on its own to make cakes or bread. Baking powder is more commonly used, and contains $NaHCO _{3}$, $Ca(H _{2}PO _{4}) _{2}$ and starch. An improved combination baking powder contains about 40% starch, 30% $NaHCO _{3}$ 20% $NaAl(SO _{4}) _{2}$ and 10% $Ca(H _{2}PO _{4}) _{2}.$ 

Answer the following questions based on above study.

$Ca(H _{2}PO _{4}) _{2}$ in baking powder:

  1. behaves as an acid in moist condition and decomposes $NaHCO _{3}$ to give $CO _{2}$
  2. behaves as a base in moist condition and gives $H _{3}PO _{4}$

  3. behaves as a binder

  4. behaves as a filler
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reaction of process:
$14 NaHCO _3+ 5 Ca(H _2PO _4)2H _2O\rightarrow 14 CO _2+ Ca _5(PO _4)3OH + 7 Na _2HPO _4+ 18 H _2O$


So Ca(H2PO4)2 in baking powder behaves as an acid  in moist condition and decomposes $NaHCO _3$ to give $CO _2$

Multiple choice chemistry substances in common use preparation, properties and uses of baking soda chemical from common salt compounds of carbon

${NaHCO _3+?\rightarrow NaCl+CO _2+H _2O}$ :

  1. ${H NO _3}$
  2. $HCl$
  3. ${Cl _2}$
  4. ${H _2SO _4}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When sodium bicarbonate reacts with $HCl$, chlorine binds with sodium and forms sodium chloride and bicarbonate ion binds with hydrogen ion of $HCl$ and forms carbonic acid. The carbonic acid further dissociates to water and carbon dioxide.

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

 $NaHCO _3$ is used as fire extinguisher.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fire extinguisher contains sodium bicarbonate in water and sulphuric acid in a separate container inside it. When the fire extinguisher is released by pressing the knob on it, the sulphuric acid mixed with sodium bicarbonate solution producing a lot of carbon dioxide gas.

$2NaHCO _3 + H _2SO _4\rightarrow Na _2SO _4 + 2H _2O + 2CO _2$ 

Carbon dioxide gas is neither combustible nor helps in combustion. It is heavier than air and offs the supply of oxygen from air and hence removes the fire. So, sodium bicarbonate is used in fire extinguishers. So the given statement is true.

Hence option A is correct.

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

Which of the following is used as fire extinguisher ?

  1. Sodium carbonate

  2. Sodium bicarbonate

  3. Sodium chloride

  4. Ammonium chloride
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sodium bicarbonate, also called sodium hydrogen carbonate, or bicarbonate of soda,$NaHCO _3$, is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as the main constituent of dry-chemical fire extinguishers.

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

With reference to sodium bicarbonate which statement is true from the options.

  1. Statement 1: Sodium bicarbonate ($NaHCO _3$)

  2. Statement 2: It reduces stomach acid

  3. Statement 3: It is used to relieve heartburn, sour stomach, or acid

  4. All are true

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

These are the right properties of Sodium Bicarbonate

Sodium bicarbonate ($NaHCO _3$)
It reduces stomach acid 

It is used to relieve heartburn, sour stomach, or acid   

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

Soda acid for extinguisher contains:

  1. sodium carbonate and nitric acid

  2. sodium hydrogen carbonate and sulphuric acid

  3. sodium carbonate and carbonic acid

  4. sodium chloride and sulphuric acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soda acid for extinguisher contains sodium hydrogen carbonate and sulphuric acid. The reaction between sodium bicarbonate solution and sulfuric acid expels pressurized water onto a fire.
$2NaHCO _3+H _2SO _4 \rightarrow Na _2SO _4+2H _2O+2CO _2$

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

 Select the correct choice:

  1. $KHCO _3$ is less soluble in water than $NaHCO _3$.
  2. $CaC _2O _4$ is soluble in water and alkalies.
  3. $Ca(HCO _3) _2$ an obtained in solid state.
  4. $BeF _2$ is water soluble but $CaF _2$ is water insoluble.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
using Fazan's rule we can say that $KHCO _3$ is less soluble in water than $NaHCO _3$

Calcium oxalate is an ionic compound with the chemical formula $CaC _2O _4$ and a salt of oxalic acid. It's highly insoluble and dissolves poorly in water. One method for dissolving calcium oxalate in the lab is the application of a compound called ethylenediaminetetraacetic acid or EDTA. EDTA is highly effective at binding the calcium ions and thereby decreasing the concentration of calcium in solution, shifting the reaction equilibrium so that more calcium oxalate will dissolve.

$NaHCO _3$ is stable to heat and normal temperature hence isolated as a solid.

However, $Ca(HCO _3) _2$ is not stable at these temperatures and hence is isolated from water, also bicarbonates of alkaline earth metals are reactive with atmospheric $CO _2$ leading to formation of  $CaCO _3$.


Hydration energy decreases down the group ,so solubility decreases down the group


Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

Which salt can furnish $H^{+}$ in its aqueous solution?

  1. $NaH _{2}PO _{2}$
  2. $Na _{2}HPO _{3}$
  3. $Na _{2}HPO _{4}$

  4. all of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Disodium hydrogenphosphite$ ( Na _2HPO _3)$ is a salt of phosphorus acid $( H _3PO _3)$, which is a dibasic acid. A dibasic acid has only two acidic or replaceable hydrogen atoms in its molecule. In $( H _3PO _3)$, the third hydrogen is directly bonded to phosphorus and so it is non-acidic.
  • $  Na _2HPO _3$ is formed when the two acidic hydrogens are replaced by sodium. In other words, this salt is the product of complete neutralisation of phosphoric acid by sodium hydroxide. It does not have any acidic hydrogen. So, it can furnish any $H^+$ in its aqueous solution.

Multiple choice chemistry allotropy of carbon preparation, properties and uses of baking soda chemical from common salt compounds of carbon

Sodium bicarbonate can react with:

  1. $Na _{2}CO _{3}$
  2. $NaOH$
  3. $NaH$
  4. $HCl$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium bicarbonate mixed with water can be used as an antacid to treat acid indigestion and heartburn. Its reaction with stomach acid produces salt, water, and carbon dioxide: 

${ NaHCO } _{ 3 }$ + $HCl$ $\rightarrow$ $NaCl$ + ${ H } _{ 2 }O$ + ${ CO } _{ 2 }$(g)

Multiple choice common laboratory equipments common laboratory apparatus and equipments laboratory equipments know about some common gases chemistry

Which piece of laboratory equipment would be used to grind large crystals into a powder?

  1. Crucible

  2. Evaporating dish

  3. Tongs

  4. Erlenmeyer flask

  5. Mortar and pestle
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation
Mortar and pestle $\rightarrow$
It is used for grinding and crushing chemicals for assorted lab procedures. It has various sizes and made of porcelain with unglazed interiors.
Hence a piece of laboratory equipment would be used to grind large crystals into a powder is mortar and pestle.
Hence the required answer is (E) Mortar and pestle.