Mix calcium sulphate with conc. HCl and forms a paste. Bring a pinch of this paste near to the flame, what colour will you obtain?

Options

A. golden yellow
B. brick red
C. crimson red
D. apple green

Answer

To solve the question, we will follow these steps:

### Step 1: Understand the Reaction
We start with calcium sulfate (CaSO4) and mix it with concentrated hydrochloric acid (HCl). The reaction can be represented as:
\[ \text{CaSO}_4 + \text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{SO}_4 \]
Here, calcium sulfate reacts with hydrochloric acid to form calcium chloride (CaCl2) and sulfuric acid (H2SO4).

**Hint:** Identify the reactants and products in the chemical reaction.

### Step 2: Analyze the Product
The main product of interest here is calcium chloride (CaCl2). This compound is important because it is responsible for the color change when exposed to flame.

**Hint:** Focus on the properties of the product formed in the reaction.

### Step 3: Flame Test
When we bring a pinch of the paste (containing calcium chloride) near to the flame, we perform a flame test. Calcium ions (Ca²⁺) produce a characteristic color when heated.

**Hint:** Recall the common colors associated with metal ions during a flame test.

### Step 4: Identify the Flame Color
For calcium ions, the flame test typically yields a brick red color. Therefore, when we bring the paste near the flame, we will observe a brick red color.

**Hint:** Look for the specific color associated with calcium in flame tests.

### Conclusion
Thus, the color obtained when a pinch of the paste is brought near to the flame is **brick red**.

**Final Answer:** Brick Red

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