Mettl Coding Skills 5

Question 1

What is the primary purpose of an abstract class in Java?

Accepted Answer

To define a template with some methods left for subclasses to implement

Answer

Abstract classes define partial implementations and enforce contracts via abstract methods that subclasses must implement.

Question 2

Which of the following correctly identifies a stack overflow?

Accepted Answer

Exceeding the call stack limit, often due to infinite recursion

Answer

A stack overflow occurs when recursive (or deeply nested) calls exhaust the fixed-size call stack.

Question 3

In CSS, which selector has the highest specificity?

Accepted Answer

ID selector (e.g., `#header`)

Answer

ID selectors carry the highest specificity weight (0,1,0,0) among standard CSS selectors.

Question 4

What is the difference between '==' and '===' in JavaScript?

Accepted Answer

'==' checks value only with type coercion; '===' checks value and type strictly

Answer

'==' performs type coercion before comparing, while '===' requires both value and type to match.

Question 5

Which of the following is an example of a linear data structure?

Accepted Answer

Linked List

Answer

A linked list is linear because elements are arranged sequentially, each pointing to the next.

Mettl Practice Test