Which of the following `"is"//"are"` incorrect?

Options

A. 1 curie `- 3.7 xx 10^(10)` dis/s
B. Actinium series starts withs `U^(238)`
C. Nuclear isomers contains the same number of protons and neutrons.
D. The decay constant is independent of the number of the substance taken.

Explanation

To determine which of the statements provided are incorrect, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1: "One Curie is equal to 3.7 × 10^10 disintegrations per second."**
- **Analysis:** The Curie (Ci) is indeed a unit of radioactivity that measures the amount of radioactive decay. It is defined as 3.7 × 10^10 disintegrations per second.
- **Conclusion:** This statement is **correct**.

2. **Statement 2: "The actinide series starts with uranium."**
- **Analysis:** The actinide series consists of elements with atomic numbers from 89 (actinium) to 103 (lawrencium). Therefore, the series starts with actinium, not uranium, which is actually the fourth element in the actinide series.
- **Conclusion:** This statement is **incorrect**.

3. **Statement 3: "Nuclear isomers contain the same number of protons and neutrons."**
- **Analysis:** Nuclear isomers are indeed different forms of the same element that have the same number of protons and neutrons but differ in energy states. This is a correct definition of nuclear isomers.
- **Conclusion:** This statement is **correct**.

4. **Statement 4: "The decay constant is independent of the number of substances taken."**
- **Analysis:** The decay constant (λ) is a characteristic of a particular radioactive isotope and does not depend on the amount of substance present. It is derived from the half-life of the substance and is indeed independent of the quantity.
- **Conclusion:** This statement is **correct**.

### Final Conclusion:
- The only incorrect statement is **Statement 2**, which claims that the actinide series starts with uranium.

### Answer:
The incorrect statement is **Statement 2**.

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