Question Discussion & Solution

1) × and ÷

Given statement: 46 ÷ 2 -­ 7 × 3 + 5 = 39

On interchanging the above signs,

46 × 2 ­- 7 ÷ 3 + 5

= 46 × 2 ­- 2.33 + 5

= 92 ­- 2.33 + 5

= 97 -­ 2.33

= 94.67 ≠ 39

2) ­- and ×

Given statement: 46 ÷ 2 -­ 7 × 3 + 5 = 39

On interchanging the above signs,

46 ÷ 2 × 7 -­ 3 + 5

= 23 × 7 -­ 3 + 5

= 161 ­- 3 + 5

= 166 ­- 3

= 163 ≠ 39

3) + and ×

Given statement: 46 ÷ 2 -­ 7 × 3 + 5 = 39

On interchanging the above signs,

46 ÷ 2 7 + 3 × 5

= 23 ­- 7 + 3 × 5

= 23 ­- 7 + 15

= 38 7

= 31 ≠ 39

4) + and ­-

Given statement: 46 ÷ 2 -­ 7 × 3 + 5 = 39

On interchanging the above signs,

46 ÷ 2 + 7 × 3 ­- 5

= 23 + 7 × 3 ­- 5

= 23 + 21 ­- 5

= 44 -­ 5

= 39

An electrician wears rubber gloves to avoid electric shock while repairing an electrical switch.

• As the human body is a good conductor of electricity.
• So it can pass through electricity from itself when it comes in contact with electricity and may get shocked or even fatality.
• As rubber is an insulator i.e. it is a non-conductor of electricity.
• So it protects the body of electricians from direct contact with electricity.

The study of individual organisms and their interaction with the environment is known as autecology.

Key Points 

• Ecology is the study of the interaction of organisms with their environment.
• Synecology and autecology is the branch of ecology.
• Synecology is the study of a group of organisms and their relation to the environment.
• Community ecology or synecology is the study of the interactions between species in communities on many spatial and temporal scales, including the distribution, structure, abundance, demography, and interactions between coexisting populations.
• For example, the study of the entire grassland ecosystem. 

CONCEPT:

• Supersonic speed: An object moving with a speed greater than the speed of sound is said to move with a supersonic speed.
  • Generally, a bullet fired from a gun and aircraft moves with supersonic speed. 
  • The speed of sound is about 768 miles per hour (1,236 kilometers per hour) at sea level.
• Supersonic speeds are described by their "Mach number".
• Mach number: The ratio of the speed of the object to the speed of sound in the air of the same temperature and density is called Mach number.
  • Supersonic includes speeds up to five times faster than the speed of sound, or Mach 5.

EXPLANATION:

• When the speed of any object exceeds the speed of sound, it is said to be traveling at Supersonic speed. So option 2 is correct.

EXTRA POINTS:

• Subsonic has a speed of less than 0.8 Mach.
• Hypersonic may have a speed between 5-10 Mach.

The correct answer is Bhairo Singh Shekhawat.

• Bhairo Singh Shekhawat who was the Chief Minister of Rajasthan took over as the 11^th Vice President of India.

Key Points

• Bhairo Singh Shekhawat was the Vice President of India from August 2002 –21 July 2007.
• He worked under the presidentship of Dr. A. P. J. Abdul Kalam.
• He served as the Chief Minister of Rajasthan in the following durations 1977 to 1980, 1990 to 1992, and 1993 to 1998.
• He was associated with Bhartiya Janta Party.

Additional Information

• Pratibha Patil served as the 12^th President of India from 2007 to 2012.
• Haridev Joshi was the 11^th Chief Minister of Rajasthan.
• Heera Lal Shastri was the first chief minister of Rajasthan.
• Mr. Ashok Gehlot is the current Chief Minister of Rajasthan.
• Mr. Sachin Pilot is the current Deputy Chief Minister of Rajasthan.