Question Discussion & Solution

Key Points Doubly linked list:
A doubly linked list is a linked data structure that consists of a set of sequentially linked records called nodes. Each node contains three fields: two link fields and one data field.
Binary tree:
A binary tree is a tree data structure in which each node has at most two children, which are referred to as the left child and the right child.

Linked list:

A linked list is a linear collection of data elements whose order is not given by their physical placement in memory. Instead, each element points to the next. It is a data structure consisting of a collection of nodes that together represent a sequence.

Queue:

A queue is a collection of entities that are maintained in a sequence and can be modified by the addition of entities at one end of the sequence and the removal of entities from the other end of the sequence.

A Doubly linked list is the efficient data structure to insert/delete a number in a stored set of numbers.

Hence the correct answer is the Doubly linked list.

The Correct Answer is Two.

 Key Points

• The water molecule is composed of two hydrogen atoms, each linked by a single chemical bond to an oxygen atom.
• Most hydrogen atoms have a nucleus consisting solely of a proton. 
• Water is a tasteless and odorless liquid at room temperature.
• It has the important ability to dissolve much other substance.

 Additional Information

• Two isotopic forms, deuterium and tritium, in which the atomic nuclei also contain one and two neutrons, respectively, are found to a small degree in water.
• Deuterium oxide (D2O) is called heavy water
• It is used as a neutron moderator in some nuclear reactors.

The correct answer is Tropical Deciduous Forests.

Key Points

• Tropical Deciduous Forests
  • These are the most widespread forests in India.
  • They are also called the monsoon forests because the trees in these forests shed their leaves during the dry season and re-grow during the monsoon. Hence, Statement 1 is correct.
  • They spread over regions that receive rainfall between 70-200 cm. 
  • The average temperature of Tropical Deciduous forests is 30oC. Hence, Statement 2 is correct.
  • The humidity in these forests lies in the range of 80-90 per cent.
  • The prime feature of these forests as trees shed their leaves in the dry season and grow back leaf in rainy seasons.
  • Major states where tropical deciduous forests are found:
    • Madhya Pradesh
    • Uttar Pradesh
    • Chhattisgarh
    • Jharkhand
    • Odisha
    • Maharashtra 
    • Some parts of Tamil Nadu and Andhra Pradesh
  • On the basis of the availability of water, these forests are further divided into
    • Moist Deciduous
    • Dry Deciduous
• Moist Deciduous forests
  • They spread over regions that receive rainfall between 100-200 cm.
  • These forests are found in the northeastern states along the foothills of the Himalayas, eastern slopes of the Western Ghats, and Odisha.
  • Teak, Sal, Shisham, Hurra, Mahua, Amla, Semul, Kusum, and Sandalwood, etc. are the main species of these forests. Hence, Statement 3 is correct.​
• Dry Deciduous forests
  • They spread over regions that receive rainfall between 70-100 cm.
  • These forests are found in the rainy areas of Peninsular India, Plains of Uttar Pradesh, and Bihar.
  • In the higher rainfall regions of the Peninsular plateau and the northern Indian plain, these forests have a parkland landscape with open stretches in which teak and other trees interspersed with patches of grass are common.
  • As the dry season begins, the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around.
  • Tendu, Palas, Amaltas, Bel, Khair, Axlewood, etc. are the common trees of these forests.

Additional Information

• Tropical Thorn Forests
  • Tropical Thorn Forests are found in areas having less than 50cm of Rainfall.
  • A variety of Grasses and Shrubs are found in these thorn forests.
  • They are present in dry and semi-dry areas of south-west Punjab, Haryana, Gujarat,
  • Rajasthan, Madhya Pradesh, and Uttar Pradesh.
  • In Tropical Thorn Forest, Trees remain leafless for the most part of the year
  • Tussocky Grass grows up to 2m in these areas. 
• ​Montane Forests​
  • Evergreen type of vegetation is prevalent in montane forests.
  • Generally, they are conical in shape so that it is easy for the snow to slide down.
  • Montane Forest is an ecosystem found in mountains.
    • These forests can be found in the higher hilly areas of Kerala and Tamil Nadu, also in the region of Eastern Himalayas to the east of 88°E longitude including the hills of Assam, West Bengal, Sikkim, Arunachal Pradesh, and Nagaland.
  • Some significant trees of the montane temperate forest are rhododendrons, ferns, oak, maple, juniper, deodar, chilgoza, etc.
• Tropical Evergreen Forests
  • ​Tropical evergreen forests are dense, multi-layered, and harbor many types of plants and animals.
  • These forests are found in the areas receiving heavy rainfall (more than 200 cm annual rainfall).
  • Therefore, these forests always appear green and are known as evergreen forests.
  • The greatest single area of tropical evergreen forest is the Amazon Basin, in the northern half of South America.
  • In India, evergreen forests are found in the western slopes of the Western Ghats in States such as Kerala and Karnataka. They are also found in the hills of Jaintia and Khasi.
  • Evergreen forests are found in the Assam Valley, the foothills of the eastern Himalayas, and the lower parts of the Naga Hills, Meghalaya, Mizoram, and Manipur.
  • Ebony, mahogany, rosewood, rubber, and cinchona are some of the commercially important trees that grow in the tropical evergreen forests.

If a mirror is placed on the line AB, then we will get this mirror image  -

The correct answer is 4°C.

• Freezing of Water:
  • As water freezes, cold water (or ice formed) comes on the surface and warm water goes down.
  • Since the freezing temperature of the water is 0ºC or 273 K.
  • So water at the bottom should be at a higher temperature.
  • Water density at 4ºC is more than the density of water at 0ºC, hence the correct option is 4ºC.

​Key Points

• Reason of low temperature at bottom of the top layer:
  • This is due to the process of convection.
  • When the temperature of the water at the top layer reaches the freezing point, it is converted to ice.
  • But ice is lighter than water, so it will not sink to the bottom.
  • So there will be ice on the top surface and water would remain at the bottom of the lake.