Skip to main content

WORKSHEET 1- Chemical Reactions and Equations

1.  Which of the given statements about the reaction below are incorrect?

a. Lead is getting reduced
b. Carbon dioxide is getting oxidised
c. Carbon is getting oxidised
d. Lead oxide is getting reduced

  • Solution:i) (a) and (b)
 2.  Fe2O3 + 2Al  Al2O3 + 2Fe

The above reaction is an example of a 
(i). Combination reaction
(ii). Double displacement reaction
(iii). Decomposition reaction
(iv). Displacement reaction
  • Solution:(iv) Displacement reaction
 3.  What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.
a. Hydrogen gas and iron chloride are produced
b. Chlorine gas and iron hydroxide are produced
c. No reaction takes place
d Iron salt and water are produced
  • Solution:Hydrogen gas and iron chloride are produced
 4.  What is a balanced chemical equation? Why should chemical equations be balanced?
  • Solution:An equation for a chemical reaction is an equation in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products. In other words, the mass and the charge are balanced on both sides of the reaction.
 5.  Translate the following statements into chemical equations and then balance them.

  • Solution:a. 3H2 + N2 ® 2NH3
    b. 2H2S + 3O2 ® 2H2O + 2SO2
    c. 3BaCl2 + Al2(SO4)3 ® 2AlCl3 + 3BaSO4
    d. 2K + 2H2O ® 2KOH + H2
 6.  Balance the following chemical equations.
b. 
c. 

  • Solution:a. 
    b. 
    c. 
    d. 
 7.  Write the balanced chemical equations for the following reactions:
a. Calcium hydroxide + Carbon dioxideCalcium carbonate + Water
b. Zinc + Silver nitrate  Zinc nitrate + Silver
c. Aluminium + Copper chlorideAluminium chloride + Copper

  • Solution:a. 
    b. 
    c. 
    d. 
 8.  Write the balanced chemical equation for the following and identify the type of reaction of each case.a. 
b. 
c. 

  • Solution:
    a. 2KBr + BaI2 ® 2KI + BaBr2 -- Double Displacement reaction
    b. ZnCO3 ® ZnO + CO2 -- Decomposition reaction
    c. H2 + Cl2 ® 2HCl -- Combination reaction
    d. Mg + 2HCl ® MgCl2 + H2  -- Displacement reaction
 9.  What is meant by exothermic and endothermic reactions? Give examples.
  • Solution:An exothermic reaction is one that releases heat.
    Reactants Product + Energy
    A simple example of this can be seen in the combustion of hydrogen and oxygen, which is a commonly used reaction in rocket engines:
    2H2 + O2  2H2O + heat
    The result is simply water vapour.
    An endothermic process describes a reaction that absorbs energy in the form of heat.
    Example:
    N2 + O2 + Heat  2NO
    If 1 mole of N2 molecule reacts with 1 mole of O2 molecule, the heat of 184 KJ has to be supplied to initiate the reaction to give 1 mole of NO molecule. This means that the bonds between N – N and O – O are so strong that they do not break easily. N2 has triple covalent bond between the two N atoms. O2 has a double covalent bond. Thus energy has to be put into the reaction to break the strong bonds. Thus the above reaction is a good example of an endothermic reaction.
 10.  Why is respiration considered an exothermic reaction?
  • Solution:During respiration, glucose combines with oxygen in the cells of our body to form carbon dioxide and water along with the production of energy.
    Glucose + oxygen  carbon dioxide + water + energy
    It is an exothermic reaction, because energy is produced during this process.

Popular posts from this blog

Acids, Bases and salts extra qus

1.    What is an acid? Solution: An acid is a hydrogen-containing chemical compound which, when dissolved in water, gives hydrogen ion (H + ) or hydrated hydrogen ion (H 2 O. H + ) or hydronium ion (H 3 O + ).   2.    What are bases and alkalies? Solution: Oxides and hydroxides of metals and metal like radicals (e.g., NH4 +  ions) are called bases. Bases ionise to give OH -  ions in aqueous solution. Bases may be soluble or insoluble in water. The soluble bases are called alkalies. Thus all alkalies are bases but all bases are not alkalies. Examples NaOH and Cu (OH) 2  both are bases, but, since NaOH is soluble in water, it is an alkali. On the other hand, since Cu (OH) 2  is insoluble in water, it is not an alkali. Other examples of alkalies are KOH, Ca (OH) 2  and NH 4 OH.   3.    Define pH. Solution: pH of a given solution is the negative logarithm to the base 10 of the hydrogen ion concentration, [H +...
Read more

Project Tiger

Project Tiger  is a wildlife conservation movement initiated in  India  in 1973 to protect  tigers . The project aims at tiger conservation in specially constituted  tiger reserves  representative of various regions throughout India and strives to maintain viable populations of Bengal tigers in their natural environment. In 2008 there were more than 40 Project Tiger reserves covering an area over 37,761 km 2  (14,580 sq mi). Project Tiger helped to increase the population of these tigers from 1,200 in the 1970s to 3,500 in 1990s. However, a 2008 census held by the Government of India revealed that the tiger population had dropped to 1,411. Since then the government has pledged US$153 million to further fund the project, set-up a Tiger Protection Force to combat  poachers , and fund the relocation of up to 200,000 villagers to minimize human-tiger conflicts. The number of tigers in India's wild has gone up by 20%, according to...
Read more

worksheet 1 Triangles

1.    Give two different examples of pair of (i) similar figures. (ii) non-similar figures. Solution: Two square of sides 4 cm and 8 cm each. A rhombus and a trapezium .   2.    State whether the following quadrilaterals are similar or not      Solution: Similar   3.    In the figure (i) and (ii), DE || BC. Find EC in (i) and AD in (ii). Solution: (i)   In  D ABC  DE is parallel to BC By Basic Proportionality Theorem  ------------------- (1) Given:  AD = 1.5 cm, DB = 3 cm, AE = 1 cm Let EC = ‘x’ cm Applying in (1) 1.5x = 3 x =  x = 2 cm EC = 2cm (ii) Since DE || BC, using BPT  …………………………. (1) Given: DB = 7.2 cm, AE = 1.8 cm, EC = 5.4 cm Let AD be = x sub. in (1) x =  =  \  AD = 2.4 cm   4.    E and F are points on the sides PQ and PR respectively of a Δ PQR. For each of the following cases, state whether EF || QR (i) PE = 3.9 cm, EQ = 3 ...
Read more