Question Discussion & Solution

Concept

The javac command in Java compiles a program from a command prompt.

It reads a Java source program from a text file and creates a compiled Java class file.

Syntax

javac filename [options]

For example, to compile a program named Abc.java, use this command:

javac Abc.java

The correct answer is Tobacco.

• In 2019, the Medical and Health Department of the Government of Rajasthan was awarded by the World Health Organization for control over Tobacco.

Key Points

• The Medical & Health Department of Rajasthan launched various campaigns against tobacco consumption at places such as schools, colleges, police stations, and government offices during 2018-19.
• As part of the tobacco-free initiatives, 1.13 crore people took a pledge against tobacco consumption at the events held in 1.56 lakh government institutions on January 30 this year, marking Martyrs’ Day.
• The award was received by the  Medical & Health Department's Additional Chief Secretary, Rohit Kumar Singh on behalf of the government

Additional Information

• World Health Organisation:
  • Established in 1948
  • Headquarters: Geneva, Switzerland.

The correct answer is Hydrocarbons.

Key Points

• The compounds which are formed by the covalent bond between carbon & hydrogen, are known as hydrocarbons.
• These are also known as 'parent compound'.
• Carbon is placed in the Second period.
• The atomic number of carbon is 6 while the weight is 12.
• Carbon needs 4 electrons to complete the octet state and it is full filled by covalent bonds.

Additional Information

•  Examples of Hydrocarbon.
• Natural Gas:
  • Natural gas contains 97% of Methane.
  • It is a colourless highly flammable gaseous hydrocarbon.
  • It is used as fuel for generating electricity and heat.
  • Natural gas is a compressed form that is used as fuel for vehicles which is known as CNG.
  • This is used for making fertilizers also, mainly ammonia.
• Methane:
  • Methane was discovered by the Italian scientist Alessandro Volta between 1776-1778 while he was studying the gases found in marshy land.
  • Melting Point- -182.5 degree
  • Boiling point- -161.5 degree
  • Methane gas is colourless and is less dense than water.
  • This gas is highly inflammable. While burning with oxygen it has a bluish flame.

CONCEPT:​

• Power of Lens: The inverse of the focal length is known as the power of the lens.
  • It shows the bending strength for the light ray of the lens.

\(P = \frac{1}{f}\)

where P is the power of the lens and f is the focal length of the lens.

• The unit of power of a lens is Dioptre when the focal length of the lens is taken in meter (m).
• The focal length of the convex lens (converging) is positive and that of the concave lens (diverging) is negative. 

CALCULATION:

Given that lens is diverging. so focal length is negative.

f = -5 cm = -0.05 m

Power of lens \(P = \frac{1}{f} =\frac{1}{-0.05} = -20 D\)

P = -20 D

So the correct answer is option 2.

Judge is the head in the court while the Principal is the head in a college.