Educational worksheet on acids, bases, and pH scale with interactive elements and chemical reactions.

Let’s go step by step through each question.

---

Q.1 Fill in the blanks with suitable words:

a) The pH scale is used to measure how acidic or alkaline a solution is.
→ This is standard — pH tells us acidity/alkalinity.

b) A solution has a pH of 2, so it is acidic.
→ pH < 7 = acidic; pH = 7 = neutral; pH > 7 = alkaline.

c) A pH test has 7 as a neutral number (indicating stronger acid).
Wait — this seems misworded. Actually, pH 7 is neutral, not indicating stronger acid. Stronger acids are lower than 7 (like pH 1–3). But the blank says “___ number (indicating stronger acid)” — that doesn’t make sense for pH 7. Let me re-read:

Original: “A pH test has 7 as a ___ number (indicating stronger acid).”

That must be a typo or error in the worksheet. Because pH 7 does NOT indicate stronger acid — it indicates neutrality. Perhaps it meant to say “(indicating neither acid nor base)” or something else? But since we have to fill based on context...

Actually, looking again — maybe it's saying: “A pH test has 7 as a ___ number” and then separately “(indicating stronger acid)” refers to low numbers? That would be confusing.

But let’s look at part d:

d) If the pH is below 7, the solution becomes more ___.

That should be “acidic”.

So perhaps c) is trying to say: “A pH test has 7 as a reference number” or “middle number”? But the phrase “(indicating stronger acid)” is attached — which is wrong for 7.

Wait — maybe it’s a trick? Or misprint?

Alternative interpretation: Maybe it’s saying “A pH test has 7 as a ___ number” and the parenthetical “(indicating stronger acid)” is describing what LOW numbers do — but that’s poorly written.

Given standard knowledge:

- pH 7 = neutral
- Below 7 = acidic
- Above 7 = alkaline

So for c), if we ignore the confusing parenthesis, the best word is neutral.

But the parenthesis says “(indicating stronger acid)” — which contradicts pH 7.

Perhaps it’s a mistake, and it should say “(indicating neither acid nor base)” or just remove the parenthesis.

Since this is a student worksheet, I’ll assume they want:

c) A pH test has 7 as a neutral number — even though the parenthesis is misleading.

Alternatively, maybe it’s “central” or “midpoint”? But “neutral” is the scientific term.

I think we go with neutral for c).

d) If the pH is below 7, the solution becomes more acidic.

Yes.

So Q.1 answers:

a) pH scale
b) acidic
c) neutral *(despite confusing parenthesis)*
d) acidic

---

Q.2 Use the pH scale below to identify range of the pH value.

The image shows a color-coded pH scale from 0 to 14, with colors: red (0-2), orange/yellow (3-5), green (6-8), blue/purple (9-14).

There are two boxes under the scale — probably asking for ranges corresponding to colors shown.

Looking at typical such worksheets:

Often, they show arrows pointing to sections and ask for the pH range.

In the image description, there are two empty boxes under the scale — likely one for acidic range and one for alkaline? Or specific color bands?

Since no exact positions are given in text, but from common versions of this worksheet:

Usually, the first box points to the left side (red-orange-yellow) → pH 0–6 (acidic)

Second box points to right side (blue-purple) → pH 8–14 (alkaline)

Sometimes they split at 7.

But since pH 7 is green (neutral), often:

Left box: 0–6 (acidic)

Right box: 8–14 (alkaline)

Or sometimes:

First box: 0–3 (strong acid)

Second box: 11–14 (strong alkali)

But without seeing exact arrow positions, we must infer.

Given the scale goes 0 to 14, and colors change, and two boxes — likely:

Box 1 (left): pH 0–6 → Acidic range

Box 2 (right): pH 8–14 → Alkaline range

Sometimes they include 7 in middle, so boxes are for non-neutral.

I think safest:

First box: 0–6

Second box: 8–14

Because 7 is neutral, separate.

---

Q.3 Fill in the blanks...

Properties of Acids | Properties of Bases

Acids turn litmus paper ___ → red

Bases turn litmus paper ___ → blue

Acids taste ___ → sour (but note: never taste lab chemicals! But theoretically)

Bases feel ___ → slippery or soapy

Acids react with metals to produce ___ gas → hydrogen

Bases react with fats/oils to form ___ → soap (saponification)

Also, acids have pH ___ → less than 7

Bases have pH ___ → greater than 7

Let’s list:

Left column (Acids):

- Turn litmus paper → red
- Taste → sour
- React with metals → produce hydrogen gas
- pH → less than 7

Right column (Bases):

- Turn litmus paper → blue
- Feel → slippery
- React with fats → form soap
- pH → greater than 7

Note: Some worksheets may use "bitter" for bases taste, but usually not emphasized due to safety. "Slippery" is key physical property.

Also, for bases reacting with fats: saponification produces soap.

So filling:

Acids:
- litmus: red
- taste: sour
- react with metals: hydrogen
- pH: less than 7

Bases:
- litmus: blue
- feel: slippery
- react with fats: soap
- pH: greater than 7

---

Q.4 Use the words in the box below to label the following acid-base reactions.

Words in box: HCl, NaOH, NaCl, H₂O

Reaction shown:

[Blue box] + [Green box] → [Light blue box] + [Clear box]

With labels underneath: ? ? = ? ?

This is clearly: Acid + Base → Salt + Water

Standard reaction: HCl + NaOH → NaCl + H₂O

So:

First reactant (blue box): HCl (acid)

Second reactant (green box): NaOH (base)

First product (light blue box): NaCl (salt)

Second product (clear box): H₂O (water)

Matches the equation.

---

Now, compiling all answers.

Final Answer:

Q.1
a) pH scale
b) acidic
c) neutral
d) acidic

Q.2
First box: 0–6
Second box: 8–14

Q.3
Acids:
- litmus paper: red
- taste: sour
- react with metals: hydrogen
- pH: less than 7

Bases:
- litmus paper: blue
- feel: slippery
- react with fats: soap
- pH: greater than 7

Q.4
HCl + NaOH → NaCl + H₂O