The most abundant intracellular cation is:
1. ${\mathrm{Na}}^{+}$
2. ${\mathrm{Ca}}^{++}$
3. ${\mathrm{H}}^{+}$
4. ${\mathrm{K}}^{+}$

Assertion: Negatively charged ions in soils are more easily lost by leaching than positively charged ions.
Reason: Soil particles in most productive soils are positively charged.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: High acidic soils can present problems for plant growth.
Reason: At low pH, aluminum ions toxicity becomes important.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: In some cases, sodium may be a ninth essential micronutrient.
Reason: Essential micronutrients are needed by the plants only in tiny quantities.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Micronutrients function in plants mainly as cofactors.
Reason: Iron is a metallic component of cytochromes.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Iron deficiency in plants can cause chlorosis.
Reason: Iron is a component of chlorophyll.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false

Assertion: A plant deficient in magnesium first shows signs of chlorosis in older leaves.
Reason: If a nutrient moves about freely, symptoms appear first in older organs.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Young seedlings frequently show mineral deficiency symptoms.
Reason: Their requirement is much lower than the requirements of older plant parts.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Excess of manganese may induce deficiencies of iron, magnesium and calcium.
Reason: Many a times, excess of an element may inhibit the uptake of another element.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: The best defined function of manganese in plants is in the splitting of water to liberate oxygen during photosynthesis.
Reason: The oxygen evolving complex is a metallo-oxo cluster comprising four manganese ions (in oxidation states ranging from +2 to +4).

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.