(English Medium) ICSE Class 10 - CISCE Important Questions

 Find the empirical formula and the molecular formula of an organic compound from the data given below : 
C = 75.92%, H = 6.32% and N = 17.76%
The vapour density of the compound is 39.5.
[C = 12, H = 1, N = 14]

The Empirical formula of an organic compound is CHCl₂.

If its relative molecular mass is 168, what is its molecular formula?

[At. Wt. C = 12, H = 1, Cl = 35.5]

Calculate:

Write the empirical formula of C₈H₁₈.

Pratik heated 11.2 grams of element ‘M’ (atomic weight 56) with 4.8 grams of element 'N' (atomic weight 16) to form a compound. Find the empirical formula of the compound obtained by Pratik.

Identify the substance underlined, in the following case

The electrolyte used for electroplating an article with silver.

Select the ion in the following case, that would get selectively discharged from the aqueous mixture of the ions listed below:

\[\ce{SO^2-_4, NO^-_3 {and} OH-}\]

Select the ion in the following case, that would get selectively discharged from the aqueous mixture of the ions listed below:

Pb²⁺, Ag⁺ and Cu²⁺

Name the following :

The process of coating of iron with zinc

Name the metallic ions that should be present in the electrolyte when an article made of copper is to be electroplated with silver.

Give reasons why In the electroplating of an article with silver, the electrolyte sodium argentocyanide solution is preferred over silver nitrate solution.

State one relevant observation for the following:

At the anode when aqueous copper sulphate solution is electrolysed using copper electrodes.

Copy and complete the following table:

Choose the correct answer from the options given below:

The electrolyte used for electroplating an article with silver is

A. Silver nitrate solution

B. Silver cyanide solution

C. Sodium argentocyanide solution

D. Nickel sulfate solution

Give one word or phrase for the following:

Electrolytic deposition of a superior metal on a baser metal.

Arrange the following according to the instruction given in bracket:

Cu²⁺, Na⁺, Zn²⁺, Ag⁺ (The order of Preferential discharge at the cathode)

Electroplating steel objects with silver involves a three-step process.

Step 1: A coating of copper is applied to the object.

Step 2: A coating of nickel is applied to the object.

Step 3: The coating of silver is applied to the object.

1. 1. A diagram of the apparatus used for step 1 is shown
      
      
      1. The chemical process taking place on the surface of the object is \[\ce{Cu^2+(aq) + 2e- ->Cu(s)}\]
         What is the observation seen on the surface of the object?
      2. Explain why the concentration of copper ions in the electrolyte remains constant throughout step 1.
2. Give two changes which would be needed in order to coat nickel on to the object in step 2.
3. Write down the reaction taking place at the positive electrode during step 3.

Give a reason for Alkali metals are good reducing agents.

Name an alloy of lead and tin.

 Match the alloys given in column I to the uses given in column II : 

X [2, 8, 7] and Y [2, 8, 2] are two elements. Using this information, complete the following:

______ is the metallic element.