Class 12 Science Flashcard

Front

What is the half-life of a first-order reaction?

Back

The half-life of a first-order reaction is the time required for the concentration of a reactant to decrease to half of its initial value. It is constant and does not depend on the initial concentration.

Front

How do you calculate the percentage of reactant remaining after a certain time in a first-order reaction?

Back

Use the formula: Remaining concentration = Initial concentration * (1/2)^(time/half-life). For example, after 30 minutes with a half-life of 10 minutes, the remaining percentage is 12.5%.

Front

What is the formula for the energy stored in a stretched spring?

Back

The energy (E) stored in a stretched spring is given by the formula E = 1/2 kx², where k is the spring constant and x is the displacement from the equilibrium position.

Front

What is the longest phase of the cell cycle?

Back

The G1 phase is the longest phase of the cell cycle, during which the cell grows and synthesizes proteins necessary for DNA replication.

Front

What is radial symmetry?

Back

Radial symmetry is a form of symmetry where body parts are arranged around a central axis, allowing for multiple lines of symmetry. An example is the sea anemone.

Front

What is the Arrhenius equation?

Back

The Arrhenius equation is k = Ae^(-Ea/RT), where k is the rate constant, A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, and T is the temperature in Kelvin.

Front

What happens to the rate constant (k) if the activation energy (Ea) is doubled?

Back

If the activation energy (Ea) is doubled while keeping temperature (T) constant, the rate constant (k) decreases exponentially.

Front

What is the significance of the spring constant (k)?

Back

The spring constant (k) measures the stiffness of a spring. A higher k value indicates a stiffer spring that requires more force to stretch or compress.

Front

What is the difference between the S phase and G1 phase in the cell cycle?

Back

The S phase is when DNA replication occurs, while the G1 phase is the initial growth phase where the cell prepares for DNA synthesis.

Front

What is an example of an animal with bilateral symmetry?

Back

An example of an animal with bilateral symmetry is a human, where the left and right sides are mirror images.