Multiple Choice Questions on Variables in Python and JavaScript

📚 Quick Study Guide

• 💡 Variables: Named storage locations in memory that hold values.
• 🐍 Python:
  • 🏷️ Dynamic typing (no need to declare variable types).
  • 🧮 Assignment using the `=` operator (e.g., `x = 10`).
  • ✒️ Variable names are case-sensitive.
• 📜 JavaScript:
  • 🔑 Uses `var`, `let`, and `const` for variable declaration.
  • 🌐 `var` has function scope (or global if declared outside a function).
  • 🧱 `let` and `const` have block scope.
  • 🔒 `const` variables must be initialized and cannot be reassigned.
• ➕ Common Data Types:
  • 🔢 Numbers (integers, floats)
  • 📜 Strings (text)
  • boolean (true/false)
  • [] Arrays (lists)
  • {} Objects (key-value pairs)
• ⚠️ Important Differences: JavaScript requires explicit declaration using `var`, `let`, or `const`, while Python does not. Scope rules also differ significantly between the two languages.

🧪 Practice Quiz

1. What is the primary difference between `var` and `let` in JavaScript?
   1. `var` has block scope, while `let` has function scope.
   2. `var` can be reassigned, while `let` cannot.
   3. `var` has function scope, while `let` has block scope.
   4. There is no difference.
2. In Python, how do you assign the value `25` to a variable named `age`?
   1. `age =: 25`
   2. `age == 25`
   3. `let age = 25`
   4. `age = 25`
3. Which of the following is NOT a valid way to declare a variable in JavaScript?
   1. `var myVar = 10;`
   2. `let myVar = 10;`
   3. `const myVar = 10;`
   4. `int myVar = 10;`
4. What is the data type of the variable `x` after the following Python code: `x = "Hello"`?
   1. Integer
   2. Float
   3. String
   4. Boolean
5. In JavaScript, which keyword is used to declare a constant variable?
   1. `var`
   2. `let`
   3. `const`
   4. `constant`
6. What will be the output of the following Python code: `x = 5; x = "updated"; print(x)`?
   1. 5
   2. "x"
   3. Error
   4. "updated"
7. Which of the following statements about variable naming is true in both Python and JavaScript?
   1. Variable names must start with a number.
   2. Variable names can only contain letters and numbers.
   3. Variable names are case-insensitive.
   4. Variable names can contain letters, numbers, and underscores.