One gram of hydrogen is found to combine with 80g of bromine and one gram of calcium (valency=2) combines with 4g of bromine then the equivalent weight of calcium is

Options

A. 10
B. 20
C. 40
D. 80

Explanation

To find the equivalent weight of calcium based on the information provided, we can follow these steps:

### Step 1: Understand the concept of equivalent weight
The equivalent weight of a substance is defined as the mass of that substance that combines with or displaces 1 mole of hydrogen or 8 grams of oxygen or 35.5 grams of chlorine. For metals, it can also be calculated using the formula:
\[ \text{Equivalent weight} = \frac{\text{Molar mass}}{\text{Valency}} \]

### Step 2: Determine the combining ratio of hydrogen and bromine
From the problem, we know that:
- 1 gram of hydrogen combines with 80 grams of bromine.

### Step 3: Calculate the equivalent weight of bromine
Since 1 gram of hydrogen combines with 80 grams of bromine, we can say that:
- 1 equivalent of hydrogen (1 g) combines with 80 g of bromine.

### Step 4: Analyze the combination of calcium and bromine
We are also given that:
- 1 gram of calcium (valency = 2) combines with 4 grams of bromine.

### Step 5: Relate the amounts of bromine combined with calcium and hydrogen
Since we know that 80 grams of bromine can combine with 1 gram of hydrogen, we can set up a proportion to find out how much calcium would combine with 80 grams of bromine:
- If 4 grams of bromine combine with 1 gram of calcium, then:
\[ \text{Amount of calcium that combines with 80 grams of bromine} = \frac{1 \text{ g of calcium}}{4 \text{ g of bromine}} \times 80 \text{ g of bromine} = 20 \text{ g of calcium} \]

### Step 6: Calculate the equivalent weight of calcium
Now, since we have established that 20 grams of calcium is equivalent to the amount of bromine that 1 gram of hydrogen can combine with, we can conclude that:
- The equivalent weight of calcium is 20 grams.

### Final Answer
Thus, the equivalent weight of calcium is **20 grams**.

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