# B+ Tree Multiple choice Questions and Answers (MCQs)

## B+ Tree Multiple choice Questions and Answers (MCQs)

 Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a B+ tree, both the internal nodes and the leaves have keys.
 A True B False
Question 1 Explanation:
In a B+ -tree, only the leaves have keys, and these keys are replicated in non-leaf nodes for defining the path for locating individual records.

 Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following is true?
 A B + tree allows only the rapid random access B B + tree allows only the rapid sequential access C B + tree allows rapid random access as well as rapid sequential access D B + tree allows rapid random access and slower sequential access
Question 2 Explanation:
The B+ -tree being a variation of B-tree allows rapid random access. In a B+ -tree the leaves are linked together, so it also provides rapid sequential access.

 Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A B+ tree can contain a maximum of 7 pointers in a node. What is the minimum number of keys in leaves?
 A 6 B 3 C 4 D 7
Question 3 Explanation:
Maximum number of pointers in a node is 7, i.e. the order of the B+ -tree is 7. In a B+ tree of order n each leaf node contains at most n - 1 key and at least ⌈(n - 1)/2⌉ keys. Therefore, a minimum number of keys each leaf can have = ⌈(7 - 1)/2⌉ = 3.

 Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following is false?
 A A B+ -tree grows downwards B A B+ -tree is balanced C In a B+ -tree, the sibling pointers allow sequential searching D B+ -tree is shallower than B-tree
Question 4 Explanation:
A B+ -tree always grows upwards. And In a B+tree - i)The path from the root to every leaf node is of the same length, so the tree is balanced. ii) Leaves are linked, so allow sequential searching. iii) An index is built with a single key per block of data rather than with one key per data record, so it is shallower than B-tree.

 Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Statement 1: When a node is split during insertion, the middle key is promoted to the parent as well as retained in right half-node.

Statement 2: When a key is deleted from the leaf, it is also deleted from the non-leaf nodes of the tree.

 A Statement 1 is true but statement 2 is false B Statement 2 is true but statement 1 is false C Both the statements are true D Both the statements are false
Question 5 Explanation:
During the split, the middle key is retained in the right half node and also promoted to parent node. When a key is deleted from the leaf, it is retained in non-leaves, because it can be still a valid separator between keys in nodes below.

There are 5 questions to complete.