What will be the output of the following code?

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

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

What will be the output of the following code?

var a = 1; { var a = 2; } console.log(a);

A). 1

B). 2

C). undefined

D). ReferenceError

Which of the following is true about 'const' variables in JavaScript?

A). They can be redeclared

B). They cannot be reassigned

C). They can be reassigned

D). They are always undefined

What is the correct syntax for declaring a variable in JavaScript?

A). let myVar = 5;

B). myVar let = 5;

C). 5 = let myVar;

D). let = myVar 5;

What will be the output of the following code?

const a = 10; a = 20; console.log(a);

A). 10

B). 20

C). Error

D). undefined

What is hoisting in JavaScript?

A). Function call before declaration

B). Variable declared at the top

C). Variable and function declaration are moved to the top

D). Variable scope

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

What will be the output of the following code?

let x; console.log(x);

A). null

B). undefined

C). 0

D). NaN

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

A). myVar

B). $myVar

C). _myVar

D). 123myVar

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