What is the default value of a variable in JavaScript if it is not initialized?

Which of the following statements is true about JavaScript's null value?

A). It represents an empty string

B). It represents a non-existent value

C). It represents a boolean value

D). It represents a number

What happens when you try to access a variable that has not been declared in JavaScript?

A). SyntaxError is thrown

B). ReferenceError is thrown

C). TypeError is thrown

D). Undefined

What is the data type of the value undefined in JavaScript?

A). String

B). Object

C). Undefined

D). Number

Which of the following statements is true about primitive data types in JavaScript?

A). They have methods and properties

B). They can be used as keys in objects

C). They are instances of Object

D). They are passed by value

What happens when you add two numbers using the + operator in JavaScript?

A). The numbers are concatenated

B). The numbers are multiplied

C). The numbers are added

D). An error occurs

Which primitive value represents absence of value or no value assigned?

A). undefined

B). null

C). 0

D). 'undefined'

What is the result of the expression 5 + '5' in JavaScript?

A). 10

B). '55'

C). '10'

D). Error

Which symbol is used to represent a boolean value in JavaScript?

A). #

B). $

C). !

D). true/false

Which of the following is a valid JavaScript symbol?

A). symbol

B). &symbol

C). #symbol

D). Symbol('description')

Which of the following statements about primitive values in JavaScript is true?

A). They are mutable

B). They are passed by reference

C). They are stored on the heap

D). They are immutable