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

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 of the following is a valid JavaScript symbol?

A). symbol

B). &symbol

C). #symbol

D). Symbol('description')

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

A). 10

B). '55'

C). '10'

D). Error

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

A). Number

B). String

C). Object

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 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

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

A). Array

B). Object

C). Function

D). String

What does the Symbol data type represent in JavaScript?

A). A unique identifier

B). A number

C). A boolean value

D). An object

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