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

Which of the following is not a primitive value in JavaScript?

A). Number

B). Boolean

C). Object

D). String

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

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

A). undefined

B). null

C). 0

D). 'undefined'

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 of the following is a valid JavaScript symbol?

A). symbol

B). &symbol

C). #symbol

D). Symbol('description')

What is a primitive value in JavaScript?

A). A complex data structure

B). A basic data type

C). A function

D). An array

What is the result of the expression undefined + null in JavaScript?

A). undefined

B). null

C). 0

D). Error

What does the Symbol data type represent in JavaScript?

A). A unique identifier

B). A number

C). A boolean value

D). An object

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

A). Number

B). String

C). Object

D). Undefined

Which of the following is a primitive data type in JavaScript?

A). Array

B). Object

C). Function

D). String