CBSE 11TH CHEMISTRY - Online Test

Answer : Option A
Explaination / Solution:

The reaction is not redox because there is no oxidation or reduction of any element (i.e. no change in oxidation state/number). 

Ba in BaCl2 is at a +2 charge because it is in group 2. On the other side of the equation Ba in BaSO4 is still +2. Cl2 on the first side of the equation is -2 (as 2 chlorines) and Cl is -2 on the other side as there are 2 of them. 

H on both sides are both +1 (but technically +2 as there are two of them). 

SO4 does not change oxidation number and always remains -2. 

So, the reaction is not a redox reaction.

Answer : Option D
Explaination / Solution:

The given equation gets stoichiometrically balanced when the coefficients ( 1 , 6 , 3 ,  2 )  starting from LHS to RHS are inserted in  given blank spaces .

Thus , the balanced equation for the reaction is ,

 

Answer : Option C
Explaination / Solution:

The reaction follows free radical mechanism in which the first step is generation of halogen free radical which is the fastest for fluorine.Hence the order.

Answer : Option C
Explaination / Solution:

The enthalpies of formation of all elements in their standard states is taken as zero.

Answer : Option C
Explaination / Solution:

In the p-block elements, the last electron enters in p-orbital of valence shell and electronic configuration of valence shell is ns2 np1-6.

Answer : Option C
Explaination / Solution:

Production of cathode rays Cathode rays are produced in the discharge tube by applying the following conditions:

• A high potential difference (>1200 V) is applied across the two aluminium electrodes.
• The length of the tube is 30 cm and the diameter is 3 cm.
• Pressure inside the tube is maintained below 0.01 mm of Hg.

Answer : Option A
Explaination / Solution:

The Earth does not directly provide Shelter which is man's basic need. we have to use different resources on earth available in different forms to convert them into objects that can be used as a shelter

Answer : Option D
Explaination / Solution:

Calgon is a process of removing permanant hardness of water. Calgon is a complex salt, Sodium hexametaphospahte Na(PO3)6 or Na6P6O18 .It acts as a ion exchange resin. It is used for softening of water.When hard water containing Ca and Mg ions is reacted with Calgon, it displaces these ions with Sodium ion, by forming a complex with itself and thus the water becomes free of these ions which cause hardness.

Answer : Option B
Explaination / Solution:

An important feature of water is its polar nature. The structure has a bent molecular geometry for the two hydrogens from the oxygen vertex. The oxygen atom also has two lone pairs of electrons.

Answer : Option B
Explaination / Solution:

Lithium due to its high hydration energy(deliquescent) forms hydrate.