Question

Major part of dry weight of a plant is derived from elements obtained from
A. Soil
B. Air
C. Water
D. Decomposing organic matter

Answer 1

Hint: The dry weight is the measurement of the mass of something when completely dried. The dry matter of plant and material consists of all its constituents excluding water.

Complete answer: The dry weight is an estimate of a body or of a body samples weight when all water has been removed means the burden of the sample, excluding the load of the water within the sample. The dry weight is decided by means of drying processes which might remove water.
Measuring plants dry weight: Since plants have a high composition of water and therefore the level of water during a plant will depend upon the quantity of water in its environment.

Steps:
> Remove the plants from the soil and wash any loose soil.
> Blot the plants removing any free surface moisture.
> Dry the plants in an oven set to low heat (100 degrees) overnight.
> Let the plants cool in an exceedingly dry environment (a Ziploc bag will keep moisture out) - during a humid environment the plant structure will take up water. Once the plants have cooled weigh them on a scale.

From the bottom to the uppermost leaf, the dry weight per unit leaf area increases, while the moisture decreases. Throughout the life cycle the dry weight of the leaves increases; the moisture increases until the time of flowering.

The major part of the dry weight of a plant comes from air within the variety of carbon because carbon is the most abundant element present within the plants and it's obtained within the kind of CO$_2$ by air.

Therefore, the correct option is b, air.

Note: The dry matter of plant and material consists of all its constituents excluding water. The dry matter of food includes carbohydrates, fats, proteins, vitamins, minerals, and antioxidants (e.g., thiocyanate, anthocyanin, and quercetin). Carbohydrates, fats, and proteins, which give the energy in foods (measured in kilocalories or kilojoules), structure ninety percent of the dry weight of a diet. Water content in foods varies widely. An outsized number of foods are over half water by weight, including boiled oatmeal (84.5%), cooked macaroni (78.4%), boiled eggs (73.2%), boiled rice (72.5%), chicken chicken (70.3%) and beefsteak (61.9%). Fruits and vegetables are 70 to 95% water. Most meats are on the average about 70% water. Breads are approximately 36% water. Some foods have a water content of but 5%, e.g., paste, crackers, and cake. Water content of dairy products is sort of variable. Butter is 15% water. Cow's milk ranges between 88-86% water. Cheese is 37% percent water. Water content of milk and dairy products varies with the proportion of butterfat so milk has an all-time low percentage of water.