What will be the output of the following code: const d = 90; d = 100; console.log(d);

How does 'let' handle variable re-declaration in the same scope?

A). Allows it

B). Silently ignores

C). Throws an error

D). Creates a new variable

What is the default scope of variables declared with the 'var' keyword in JavaScript?

A). Block scope

B). Function scope

C). Module scope

D). Block and function scope

How do 'var' declarations handle hoisting?

A). They are not hoisted

B). Only the assignment is hoisted

C). Only the declaration is hoisted

D). Both declaration and assignment are hoisted

What will be the output of the following code: console.log(a); var a = 50;

A). 50

B). undefined

C). Error

D). null

Which keyword allows block-scoped variable declaration?

A). var

B). let

C). const

D). Both B and C

Which of the following statements is true about 'const'?

A). It allows re-declaration

B). It allows reassignment

C). It is block-scoped

D). It is function-scoped

What will be the output of the following code: if (true) { let b = 60; } console.log(b);

A). 60

B). undefined

C). Error

D). null

What will be the output of the following code: let y = 10; let y = 20; console.log(y);

A). 10

B). 20

C). Error

D). undefined

Which keyword should be used by default to declare variables in modern JavaScript?

A). var

B). let

C). const

D). Either B or C

Which keyword is used for declaring variables that should not change?

A). var

B). let

C). const

D). all of the above