What will be the output of the following code?

let x; console.log(x);

Which statement is true about variables in JavaScript?

A). They must be declared before use

B). They can only hold numbers

C). They are statically typed

D). They are strongly typed

What will be the output of the following code?

console.log(a); var a = 10;

A). 10

B). undefined

C). Error

D). null

Which of the following is NOT a valid variable name in JavaScript?

A). myVar

B). $myVar

C). _myVar

D). 123myVar

What will be the output of the following code?

let a = 1; let b = 2; let c = a + b; console.log(c);

A). 12

B). 12

C). 3

D). NaN

What is the difference between let and var?

A). let is function-scoped, var is block-scoped

B). let is block-scoped, var is function-scoped

C). Both are block-scoped

D). Both are function-scoped

Can variables declared with 'var' be redeclared in the same scope?

A). Yes

B). No

C). Only inside a function

D). Only inside a loop

Can you reassign a value to a variable declared with let?

A). Yes

B). No

C). Only in strict mode

D). Only inside a block

Which of the following is a valid variable name in JavaScript?

A). 2name

B). _name

C). #name

D).

Which keyword should be used to declare a block-scoped variable?

A). var

B). let

C). const

D). Both let and const

Which of the following is true about variable naming conventions in JavaScript?

A). Variable names can start with a number

B). Variable names are case-insensitive

C). Variable names can include spaces

D). Variable names are case-sensitive