Answer the following questions 99 points guaranteed
(i) What is Aqua Regia ? Give its any one use.
(ii) Why does HCL(g) not conduct electricity when dissolved in toluene ?
(iii) What is Universal indicator ? Give its use.
(iv) Name the compound which is obtained
(1) from baking soda & is used to remove permanent hardness of water.
(2) Write its chemical formula.
(3) What happened when it is recrystal from its aqueous solution ?
(v) “Sodium Hydrogen Carbonate isbasic salt.” Justify this statement. (vi) What is tooth enamel chemically ? State the condition when it starts corroding. What happens when food particles left in the mouth after eating degrade ? Why do doctors suggest use of tooth paste to prevent tooth decay ?
(vii) Write the name of gland associated with brain. Which problem is caused dur to
deficiency of the hormone released by this gland ?
(viii) With the help of a flow chart ,highlight the various types of plant movements with suitable examples.
(ix) “Thebreathing cycle is rhythmic whereas exchange of gases is a continuous process.” Justifythis statement.
(x) Give the role of valves present in Human Heart.
Answers
Answer:
(i) What is Aqua Regia ? Give its any one use.
a mixture of concentrated nitric and hydrochloric acids. It is a highly corrosive liquid able to attack gold and other resistant substances.
(ii) Why does HCL(g) not conduct electricity when dissolved in toluene ?
HCl gas dissolved in toluene does.not conduct electricity while HCl gas dissolved in water conducts electricity. ... Toluene is a non polar organic solvent. Toluene do not ionises HCl to form ions. The solution which contains free ions can conduct electricity.
(iii) What is Universal indicator ? Give its use.
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions.
...
Universal indicator.
Indicator Bromothymol blue
Low pH colour Yellow
Transition pH range 6.0 – 7.6
High pH colour Blue
(iv) Name the compound which is obtained
1)Sodium carbonate
2)Na2CO3
3)Reactive Recrystallization of Sodium Bicarbonate. The thermal decomposition of sodium bicarbonate, NaHCO3, in mixed solvents composed of ethylene glycol and water was found to occur solution mediated; i.e., bicarbonate ions (HCO3-) convert in solution to carbonate ions (CO32-), carbon dioxide, and water.
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