Radio buttons and checkboxes in HTML - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding radio button grouping

What happens when multiple radio buttons share the same name attribute in an HTML form?

A Only one radio button in the group can be selected at a time.

B All radio buttons can be selected independently.

C The radio buttons become disabled automatically.

D The radio buttons behave like checkboxes and allow multiple selections.

💡 Hint

Think about how radio buttons are designed to let users pick one option from many.

Radio buttons with the same name attribute form a group where only one option can be selected at a time. Selecting another option deselects the previous one.

📝 Syntax

intermediate

Correct checkbox syntax

Which option shows the correct HTML syntax for a checkbox input with label 'Subscribe'?

A <input type="checkbox" id="subscribe"> <label for="subscribe">Subscribe</label>

B <checkbox id="subscribe">Subscribe</checkbox>

C <input type="check" id="subscribe"> <label>Subscribe</label>

D <input type="checkbox" name="subscribe">Subscribe</input>

💡 Hint

Remember the correct input type and how labels link to inputs.

The correct way is to use <input type="checkbox"> and a <label> with a matching for attribute to the input's id.

❓ rendering

advanced

Visual result of grouped radio buttons

What will the user see when this HTML code is rendered in a browser?

<form>
  <input type="radio" name="color" id="red" value="red">
  <label for="red">Red</label>
  <input type="radio" name="color" id="blue" value="blue">
  <label for="blue">Blue</label>
</form>

A Two buttons labeled 'Red' and 'Blue' that submit the form when clicked.

B Two checkboxes labeled 'Red' and 'Blue' that can be selected independently.

C Two radio buttons labeled 'Red' and 'Blue' where only one can be selected at a time.

D Two text input fields labeled 'Red' and 'Blue' for typing.

💡 Hint

Look at the input types and the shared name attribute.

The code creates two radio buttons with the same name, so the user can select only one color at a time.

❓ accessibility

advanced

Improving checkbox accessibility

Which option best improves accessibility for a checkbox input labeled 'Accept Terms'?

A <input type="checkbox" id="terms"><label>Accept Terms</label>

B <input type="checkbox" aria-labelledby="terms-label"><span id="terms-label">Accept Terms</span>

C <input type="checkbox" id="terms" aria-label="Accept Terms">

D <input type="checkbox" id="terms"><label for="terms">Accept Terms</label>

💡 Hint

Consider how screen readers associate labels with inputs.

The best practice is to use <label> with a matching for attribute to the input's id. This ensures screen readers correctly announce the label and makes the label text clickable for better usability.

❓ selector

expert

CSS selector for checked checkboxes

Which CSS selector correctly styles only the checkboxes that are checked?

A input[type="checkbox"]:check { background-color: lightgreen; }

B input[type="checkbox"]:checked { background-color: lightgreen; }

C input:checked[type="checkbox"] { background-color: lightgreen; }

D input[type="checkbox" checked] { background-color: lightgreen; }

💡 Hint

Look for the correct pseudo-class syntax for checked inputs.

The :checked pseudo-class selects checked checkboxes. The syntax must be input[type="checkbox"]:checked.

Practice

1. Which input type allows a user to select only one option from a group?
<input type="?">

easy

A. button

B. checkbox

C. radio

D. text

Solution

1. Step 1: Understand input types

   The radio input type is designed for selecting one option from many.

2. Step 2: Compare with other types

   checkbox allows multiple selections, text is for typing, and button triggers actions.

3. Final Answer:

   radio -> Option C

4. Quick Check:

   Single choice = radio [OK]

Hint: Radio = one choice, Checkbox = many choices [OK]

Common Mistakes:

• Confusing checkbox with radio
• Thinking text input allows selection
• Using button for selection

2. Which of the following is the correct syntax to create a checkbox with label "Subscribe"?

easy

A. Subscribe

B. Subscribe

C. Subscribe

D. Subscribe

Solution

1. Step 1: Check input and label usage

   The correct checkbox uses <input type="checkbox"> and a <label> with matching for attribute.

2. Step 2: Identify invalid syntax

   The other options use invalid syntax: A uses a non-existent <checkbox> tag, B incorrectly closes the input with text inside, and D uses an invalid checkbox attribute.

3. Final Answer:

   <input type="checkbox" id="sub"><label for="sub">Subscribe</label> -> Option B

4. Quick Check:

   Checkbox + label with for = correct syntax [OK]

Hint: Use with [OK]

Common Mistakes:

• Using non-existent <checkbox> tag
• Missing type attribute
• Not linking label with for attribute

3. What will be the result when this HTML is rendered?

<form>
  <input type="radio" name="color" id="red" value="Red"><label for="red">Red</label>
  <input type="radio" name="color" id="blue" value="Blue" checked><label for="blue">Blue</label>
  <input type="radio" name="color" id="green" value="Green"><label for="green">Green</label>
</form>

medium

A. Only the Blue radio button is selected by default

B. All three radio buttons are selected

C. No radio buttons are selected by default

D. The Green radio button is selected by default

Solution

1. Step 1: Identify checked attribute

   The Blue radio button has the checked attribute, so it is selected by default.

2. Step 2: Understand radio group behavior

   Only one radio button in a group (same name) can be selected at a time.

3. Final Answer:

   Only the Blue radio button is selected by default -> Option A

4. Quick Check:

   Checked attribute sets default selection [OK]

Hint: Look for checked attribute to find default selected radio [OK]

Common Mistakes:

• Assuming multiple radios can be selected
• Ignoring the checked attribute
• Confusing radio with checkbox behavior

4. This code snippet is intended to create two checkboxes with labels, but only one label works correctly. What is the error?

<input type="checkbox" id="news"><label for="news">News</label>
<input type="checkbox" id="updates"><label>Updates</label>

medium

A. The second label is missing the for attribute linking it to the checkbox

B. The first checkbox is missing a name attribute

C. Checkboxes cannot have labels

D. The id attribute should be on the label, not the input

Solution

1. Step 1: Check label associations

   The first label uses for="news" linking it to the checkbox with id "news".

2. Step 2: Identify missing for attribute

   The second label lacks a for attribute, so it is not linked to the checkbox with id "updates".

3. Final Answer:

   The second label is missing the for attribute linking it to the checkbox -> Option A

4. Quick Check:

   Label needs for attribute to link input [OK]

Hint: Labels must have for attribute matching input id [OK]

Common Mistakes:

• Assuming name attribute is required for labels
• Thinking labels can't be used with checkboxes
• Placing id on label instead of input

5. You want to create a form where users can select their favorite fruits. They can pick any number of fruits, but only one fruit size (Small, Medium, Large). Which input types should you use for fruits and sizes respectively?

hard

A. Radio buttons for both fruits and sizes

B. Radio buttons for fruits, Checkboxes for sizes

C. Checkboxes for both fruits and sizes

D. Checkboxes for fruits, Radio buttons for sizes

Solution

1. Step 1: Understand selection rules

   Users can pick multiple fruits, so checkboxes are suitable for fruits.

2. Step 2: Single choice for size

   Only one size can be selected, so radio buttons are suitable for sizes.

3. Final Answer:

   Checkboxes for fruits, Radio buttons for sizes -> Option D

4. Quick Check:

   Multiple choice = checkbox, single choice = radio [OK]

Hint: Multiple selections use checkbox; single selection uses radio [OK]

Common Mistakes:

• Using radio buttons for multiple selections
• Using checkboxes for single selection
• Not grouping radio buttons by name