Cell merging in HTML - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ rendering

intermediate

What is the visual result of this table with merged cells?

Look at this HTML table code. What will you see in the browser?

HTML

<table border="1">
  <tr>
    <td rowspan="2">A</td>
    <td>B</td>
  </tr>
  <tr>
    <td>C</td>
  </tr>
</table>

A A and C merged horizontally in the first row, B in the second row.

B A in the first column spanning two rows, B and C stacked vertically in the second column.

C A and B in the first row, C in a new row but under A.

D A, B, and C all in one row horizontally.

💡 Hint

Remember, rowspan merges cells vertically.

The cell with rowspan="2" merges vertically across two rows, so 'A' covers the first column in both rows. 'B' and 'C' appear in the second column stacked vertically.

❓ rendering

intermediate

What does colspan="3" do in this table?

Check this table code. What will the first row look like in the browser?

HTML

<table border="1">
  <tr>
    <td colspan="3">Header</td>
  </tr>
  <tr>
    <td>1</td>
    <td>2</td>
    <td>3</td>
  </tr>
</table>

A The first row has three cells labeled 'Header', 'Header', 'Header'.

B The first row has three separate cells labeled 'Header', '2', and '3'.

C The first row has one cell spanning across three columns labeled 'Header'.

D The first row has one cell labeled 'Header' but only spans one column.

💡 Hint

colspan merges cells horizontally.

The cell with colspan="3" stretches across three columns, so the entire first row is one big cell labeled 'Header'.

📝 Syntax

advanced

What error does this table code cause?

This HTML snippet tries to merge cells but has a mistake. What error or problem will happen?

HTML

<table border="1">
  <tr>
    <td colspan="2">X</td>
    <td>Y</td>
  </tr>
  <tr>
    <td>A</td>
    <td>B</td>
  </tr>
</table>

A The second row has fewer cells than the first, causing layout issues.

B The browser shows an extra empty cell in the second row.

C The table renders normally with no visible error.

D The browser throws a syntax error and does not render the table.

💡 Hint

Count columns in each row after merging.

The first row has 3 columns total (colspan=2 plus one cell). The second row has only 2 cells, so the table layout is uneven and may cause rendering issues.

❓ accessibility

advanced

Which attribute improves accessibility for merged table cells?

When merging cells in a table, which attribute helps screen readers understand the table structure better?

A aria-colspan

B aria-rowspan

C tabindex

D scope

💡 Hint

This attribute defines the cell's role as header for rows or columns.

The 'scope' attribute on elements tells screen readers if the header applies to a row, column, or group, improving accessibility especially with merged cells.

❓ selector

expert

Which CSS selector targets all cells merged horizontally with colspan?

You want to style all table cells that have a colspan attribute. Which CSS selector works?

A td[colspan]

B td.colspan

C td#colspan

D td::colspan

💡 Hint

Attribute selectors use square brackets.

The selector td[colspan] selects all elements with a colspan attribute, regardless of its value.

Practice

1. What does the colspan attribute do in an HTML table?

easy

A. It merges cells horizontally across columns.

B. It merges cells vertically across rows.

C. It changes the color of a cell.

D. It adds a border around a cell.

Solution

1. Step 1: Understand the purpose of colspan

   The colspan attribute is used in a table cell to make it span across multiple columns horizontally.

2. Step 2: Compare with rowspan

   rowspan merges cells vertically across rows, so it is different from colspan.

3. Final Answer:

   It merges cells horizontally across columns. -> Option A

4. Quick Check:

   colspan = horizontal merge [OK]

Hint: Remember: colSpan = column span (horizontal) [OK]

Common Mistakes:

• Confusing colspan with rowspan
• Thinking colspan changes cell style
• Assuming colspan merges rows

2. Which of the following is the correct syntax to merge two columns in a table cell?

easy

A. <td rowspan='2'>Merged</td>

B. <td merge='2'>Merged</td>

C. <td colspan='2'>Merged</td>

D. <td span='2'>Merged</td>

Solution

1. Step 1: Identify the correct attribute for column merging

   The attribute to merge columns is colspan, so it should be used as colspan='2'.

2. Step 2: Check syntax correctness

   <td colspan='2'>Merged</td> uses the correct attribute and syntax: <td colspan='2'>Merged</td>. Other options use wrong attributes or invalid syntax.

3. Final Answer:

   <td colspan='2'>Merged</td> -> Option C

4. Quick Check:

   Correct attribute for columns = colspan [OK]

Hint: Use colspan='number' to merge columns [OK]

Common Mistakes:

• Using rowspan instead of colspan
• Using non-existent attributes like merge or span
• Missing quotes around attribute value

3. What will be the visual result of this HTML snippet?

<table border='1'>
  <tr>
    <td rowspan='2'>A</td>
    <td>B</td>
  </tr>
  <tr>
    <td>C</td>
  </tr>
</table>

medium

A. All cells appear in a single row.

B. Cell 'A' spans two rows vertically, cells 'B' and 'C' are side by side horizontally.

C. Cell 'A' spans two columns horizontally, cells 'B' and 'C' are below 'A'.

D. Cell 'A' spans two rows vertically, cells 'B' and 'C' are stacked vertically next to 'A'.

Solution

1. Step 1: Understand rowspan effect

   The rowspan='2' on cell 'A' makes it cover two rows vertically in the first column.

2. Step 2: Analyze placement of cells 'B' and 'C'

   Cell 'B' is in the first row, second column; cell 'C' is in the second row, second column. They stack vertically next to the tall 'A' cell.

3. Final Answer:

   Cell 'A' spans two rows vertically, cells 'B' and 'C' are stacked vertically next to 'A'. -> Option D

4. Quick Check:

   rowspan = vertical merge [OK]

Hint: Rowspan stacks cells vertically beside merged cell [OK]

Common Mistakes:

• Thinking rowspan merges columns horizontally
• Assuming cells B and C are side by side horizontally
• Confusing rowspan with colspan

4. Identify the error in this table code that tries to merge cells across two columns:

<table border='1'>
  <tr>
    <td colspan='2'>Merged</td>
    <td>Cell 3</td>
  </tr>
  <tr>
    <td>Cell 4</td>
    <td>Cell 5</td>
  </tr>
</table>

medium

A. Second row has only two cells but first row has three columns, causing layout mismatch.

B. The colspan attribute value should be '3' instead of '2'.

C. The colspan attribute is not allowed on td elements.

D. The table is missing a thead section.

Solution

1. Step 1: Count columns in first row

   The first row has a cell with colspan='2' plus one more cell, so total columns = 2 + 1 = 3.

2. Step 2: Count columns in second row

   The second row has only two cells, so only 2 columns, which causes a mismatch in table layout.

3. Final Answer:

   Second row has only two cells but first row has three columns, causing layout mismatch. -> Option A

4. Quick Check:

   Column count must match in all rows [OK]

Hint: Ensure all rows have same total columns after colspan [OK]

Common Mistakes:

• Ignoring column count mismatch
• Thinking colspan value must match total columns
• Believing colspan is invalid on <td>

5. You want to create a table where the top-left cell spans 2 rows and 3 columns. Which is the correct way to write this cell?

hard

A. <td rowspan='3' colspan='2'>Top Left</td>

B. <td rowspan='2' colspan='3'>Top Left</td>

C. <td colspan='2' rowspan='3'>Top Left</td>

D. <td colspan='3'>Top Left</td>

Solution

1. Step 1: Identify correct rowspan and colspan values

   The cell should span 2 rows vertically and 3 columns horizontally, so rowspan='2' and colspan='3' are needed.

2. Step 2: Check attribute order and correctness

   Attributes can be in any order, but <td rowspan='2' colspan='3'>Top Left</td> correctly uses rowspan='2' and colspan='3'. Other options have swapped or incorrect values.

3. Final Answer:

   <td rowspan='2' colspan='3'>Top Left</td> -> Option B

4. Quick Check:

   Rowspan = rows, colspan = columns [OK]

Hint: Use rowspan for rows, colspan for columns together [OK]

Common Mistakes:

• Swapping rowspan and colspan values
• Using wrong numbers for spans
• Omitting one of the attributes