In the plot of concentration of reactant versus time, the tangent at any instant of time has a ……………. Slope (positive or negative or zero).

Answer

To solve the question regarding the slope of the tangent in a plot of concentration of reactant versus time, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Graph**:
- The graph in question plots the concentration of a reactant (on the y-axis) against time (on the x-axis).

2. **Behavior of Reactants Over Time**:
- In a typical chemical reaction, as time progresses, the reactants are converted into products. This means that the concentration of the reactants decreases over time.

3. **Identifying the Slope**:
- The slope of a tangent line on a graph indicates the rate of change of the y-variable (concentration of reactant) with respect to the x-variable (time).
- Since the concentration of the reactant is decreasing as time increases, the slope of the tangent line at any point in time will be negative.

4. **Conclusion**:
- Therefore, the tangent at any instant of time in the plot of concentration of reactant versus time has a **negative slope**.

### Final Answer:
The tangent at any instant of time has a **negative slope**.

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