Ncert Solutions Chemistry Class 11th

9.51. Dihydrogen, under certain reaction conditions, combines with almost all elements, except noble gases, to form binary compounds, called hydrides. If 'E' is the symbol of an element then hydride can be expressed as EH_x (e.g., MgH₂) or E_mH_n (e.g., B₂H₆).

The hydrides are classified into three

9.50. The basic principle of hydrogen economy is the transportation and storage ofenergy in the form of liquid or gaseous dihydrogen. Advantage of hydrogen economyis that energy is transmitted in the form ofdihydrogen and not as electric power. It is for the first time in the history of India t

9.49. Some of the uses of H₂O₂ are listed below:

(i) In daily life it is used as a hair bleach andas a mild disinfectant. As an antiseptic it is sold in the market as perhydrol.

(ii) It is used to manufacture chemicals like sodium perborate and percarbonate, which are used in high quality deter

9.48. Dihydrogen is inactive at room temperature because of very highnegative dissociation enthalpy, it combines with almost all the elements under appropriate conditions to form hydrides.

9.47. The H–H bond dissociation enthalpy of dihydrogen (435.88 kJ mol–1) is the highest for a single bond between two atoms of any elements. This property is made use of in the atomic hydrogen torch which generates a temperature of ~4000K and is ideal for welding of high melting metals.

9.46.  (b) Reducing agent

9.45.  (a) H₂O₂ has planar structure.

9.44.  (a) H+ can exist freely.

9.43.  (d) Calgon forms precipitates with Ca²⁺ and Mg²⁺.