Which among the following statement(s) is (are) true?
Exposure of silver chloride to sunlight for a long duration turns grey due to
(i) The formation of silver by decomposition of silver chloride.
(ii) Sublimation of silver chloride.
(iii) Decomposition of chlorine gas from silver chloride.
(iv) Oxidation of silver chloride.
Silver chloride turns grey due to the formation of silver by decomposition of silver chloride.
Which of the following are combination reactions ?
(i) 2KClO3 2KCl + 3O2
(ii) MGO + H2O → Mg(OH)2
(iii) 4Al + 3O2 → 2Al2O3
(iv) Zn +FeSO4 → ZnSO4 +Fe
Combination reactions are those in which two or more reactants react to give one product only.
What is observed when a solution of potassium iodide is added to lead nitrate solution ?
When a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube, the precipitation of a yellowish solid is observed. This yellowish solid is lead iodide. Potassium nitrate is formed along with lead iodide.
This is an example of double displacement reaction.
Also , as yellow precipitate is formed , this is also an example of precipitation reaction
Balanced Equation: Pb(NO3)2 + 2KI → 2KNO3 + PbI2
Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved ?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
In the given reaction, there is an exchange of ions between the reactants, thus it is a double displacement reaction. Also, white precipitate of barium sulphate is formed as a product, thus it is also an example of precipitation reaction.
Which of the following statements about the given reaction are correct ?
3Fe(s) + 4H2O(g) → Fe3O4(g) + 6H2 (g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as an oxidising agent
In the given reaction, there is addition of oxygen to iron metal and it is oxidised. Also, there is removal of hydrogen from the water and thus, water is reduced. A substance which causes oxidation of other chemical species in a chemical reaction and itself undergoes reduction, is known as an oxidising agent. Thus, in given reaction, water is acting as an oxidising agent.
Which of the following is not a decomposition reaction ?
A decomposition reaction occurs when an energy is supplied to a compound causing it to decompose (break down) into multiple different chemical substances.
But in 'C' it is a combination reaction
The formula of Ammonium phosphate is
Ammonium phosphate is an ammonium salt of orthophosphoric acid. It is a highly unstable compound with the formula (NH4)3PO4. The salt is a colourless, odourless, crystalline solid which is not soluble in water.
Which of the following reactions will not take place?
Mg is more reactive than Zn. So Zn cannot displace Mg. Therefore,option C is the answer.
(i) gain of electron
(ii) loss of electron
(iii) addition of oxygen or electronegative element
(iv) removal of hydrogen or electropositive element
Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. The opposite process is called reduction, which occurs when there is a gain of electrons or the oxidation state of an atom, molecule, or ion decreases.
The addition of oxygen to an element or compound or Removal of hydrogen from a compound is known as oxidation.
In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?
Lead sulphate being insoluble will not dissociate to give lead ions. Hence precipitation of lead iodide will not be possible with lead sulphate.
Lead acetate is a colourless compound. On coming in contact with potassium iodide crystal, the formation of lead iodide occurs that is bright yellow in colour. Also, other salts, ammonium nitrate and potassium sulphate do not possess the lead ion, therefore lead iodide can not be formed using them.