Chemical Reaction and Equation (HOTS) (Subjectives)
Q1:- When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.
- (a) Name any two metals which can behave like metal X.
- (b) Name any two acids which can behave like acid Y.
- (c) Name gas Z.
- (d) Is the gas Z lighter than or heavier than air?
- (e) Is the reaction between metal X and dilute acid Y exothermic or endothermic?
- (f) By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate the physical states of all the reactants and products.
A)Zinc, Iron(Fe) .... etc.. are the metals that behave like X.
B)Hydrochloric acid, Hydrosulphuric Acid are the acids that behave like acid Y.
C)Gas Z is Hydrogen. Hydrogen gas is evolved which burns readily by making a little explosion
D)Hydrogen gas is lighter than air.
E)The reaction between metal X and Dilute Acid Y is an exothermic reaction.
F)Equation of the reaction is given in pic.
Q2:- When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during whitewashing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
- (a) What could be solid X ? Write its chemical formula.
- (b) What could be product Y? Write its chemical formula.
- (c) What is the common name of the solution of Y which is used for testing carbon dioxide gas?
- (d) Write the chemical equation of the reaction which takes place on adding water to solid X.
- (e) Which characteristic of chemical reactions is illustrated by this example?
A)Calcium Oxide is the white solid X . Cao is the chemical formula.
B)Calcium Hydroxide is the product Y. Ca(OH)2 is the chemical formula.
C)Calcium hydroxide is also called lime Water. Hence, it's the Common name of Solution Y.
D)Pic of the Equation is given.
E)In this reaction, calcium oxide(Quick lime) reacts with Water and produces Calcium hydroxide (Slaked lime) and a large amount of heat. Hence, it's an exothermic reaction.
Q3:- A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.
- (a) What is substance P ? Write its common name as well as a chemical formula.
- (b) What is substance Q?
- (c) What is gas R?
- (d) What is substance S? What is its clear solution known as?
- (e) What is substance T? Name any two natural forms in which substance T occurs in nature.
A)The Substance P is calcium carbonate. It's very hard. It is used in the construction of many buildings. Its chemical formula Is:- CaCO3
B)Solid Q is Calcium oxide.
C)Gas R is Carbon Dioxide. This evolves during the Decomposition of calcium carbonate
D)Substance S is Calcium hydroxide. It forms when Calcium oxide reacts with water. It is known aa a clear solution.
E)Substance T is again Calcium carbonate's Two natural forms is Limewater and Marble.
Q4:- When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution.
- (a) What do you think substance X is likely to be?
- (b) Name the substance which the yellow solid consists of.
- (c) Which characteristic of chemical reactions is illustrated by this example?
- (d) Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.
A)Lead Nitrate is the Substance X
B)Lead Iodide is the yellow precipitate
C)Change in colour as well as the formation of the precipitate. (A Yellow precipitate is formed).
D)Pic of the Equation is given.
Q5:- A silvery-white metal X has taken in the form of a ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substance Z.
- (a) What could metal X be?
- (b) What is powder Y?
- (c) With which substance metal X combines to form powder Y?
- (d) What is substance Z? Name one domestic use of substance Z.
- (e) Write a balanced chemical equation of the reaction which takes place when metal X burns in air to form powder Y.
A)Magnesium is the metal X.It is silvery White in colour.
B)Magnesium oxide is the white powder
Magnesium ribbon reacts with oxygen to form the white powder Magnesium oxide.
D)Magnesium Hydroxide is substance Z.
It is used as an antacid for indigestion.
E)Pic of the Equation is given.
Q6:- When a black metal compound XO is heated with a colourless gas Y2, then metal X and another compound Y2O are formed. Metal X is red-brown in colour which does not react with dilute acids at all. Gas Y2 can be prepared by the action of dilute acid on any active metal. The compound Y2O is a liquid at room temperature which can turn anhydrous copper sulphate blue.
- (a) What do you think is metal X?
- (b) What could be gas Y2?
- (c) What is compound XO?
- (d) What is compound Y2O?
- (e) Write the chemical equation of the reaction which takes place on heating XO with Y2.
- (f) What type of chemical reaction is illustrated in the above equation
A) X is:- Cu (Copper ). It is red-brown in colour .it does not react with acids.
B) Gas Y2 is Hydrogen.
C) Compound XO is CuO
D) Compound Y20 is H20.
E) CuO + H2 --->Cu + H2O
F) Displacement reaction ( also a redox reaction)
Q7:- When a mixture of gases X and Y is compressed to 300 atm pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300°C), then an organic compound Z having the molecular formula CH4O is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of dilute acid on an active metal, and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.
- (a) What are X, Y and Z?
- (b) Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.
A)X = Carbon Monoxide (CO ), Y = Hydrogen , Z = Methanol (Methyl Alcohol)
B)The pic of the equation is given
[Note. The molecular formula CH4O for compound Z
tells us that one molecule of this compound contains 1 carbon atom, 4 hydrogen atoms and 1 oxygen atom (CH4O = CH3OH)]
Q8:- The white solid compound A decomposes quite rapidly on heating in the presence of a black substance X to form a solid compound B and a gas C. When an aqueous solution of compound B is reacted with silver nitrate solution, then a white precipitate of silver chloride is obtained along with a potassium nitrate solution. Gas C does not burn itself but helps burn other things.
- (a) What is compound A?
- (b) What is compound B?
- (c) What is gas C?
- (d) What do you think is the black substance X ? What is its function?
- (e) What is the general name of substances like X?
B)Potassium Chloride, KCL
D)Manganese Dioxide(Black), It Acts as a catalyst In the decomposition of potassium chlorate.
Q9:- A metal salt MX, when exposed to light, splits up to form metal M and a gas X2. Metal M is used in making ornaments whereas gas X2 is used in making bleaching powder. The salt MX is itself used in black and white photography.
- (a) What do you think metal M is?
- (b) What could be gas X2?
- (c) Name the metal salt MX.
- (d) Name any two salt solutions which on mixing together can produce a precipitate of salt MX.
- (e) What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction.
C)Silver chloride ,AgCl
D)Silver Nitrate and Sodium chloride
E)Photolytic Decomposition takes place when salt MX is exposed to light. Pic of the Equation is given.
Q10:- A red-brown metal X forms a salt XSO4. When hydrogen sulphide gas is passed through an aqueous solution of XSO4, then a black precipitate of XS is formed along with the sulphuric acid solution.
- (a) What could the salt XSO4 be?
- (b) What is the colour of salt XSO4?
- (c) Name the black precipitate XS.
- (d) By using the formula of the salt obtained in (a) above, write an equation of the reaction which takes place when hydrogen sulphide gas is passed through its aqueous solution.
- (e) What type of chemical reaction takes place in this case?
D)Pic is given of the equation