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

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 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

Which keyword allows block-scoped variable declaration?

A). var

B). let

C). const

D). Both B and C

What will be the output of the following code: var x = 5; var x = 10; console.log(x);

A). 5

B). 10

C). Error

D). undefined

What will be the output of the following code: const z = 30; z = 40; console.log(z);

A). 30

B). 40

C). Error

D). undefined

Can 'const' be used to declare an array or object?

A). No, only primitives

B). Yes, but the reference can't change

C). Yes, and the content can't change

D). No

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

Can you re-declare a variable using 'const' in the same scope?

A). Yes

B). No

C). Only in functions

D). Only in loops

What will be the output of the following code: var e = 110; if (true) { var e = 120; } console.log(e);

A). 110

B). 120

C). Error

D). undefined