Math Sample Papers- I For Class 9 & 10

The standard value of the least distance of distinct vision for the normal human eye is 25 cm. This means that the minimum distance at which a person with normal vision can see an object clearly without any blurriness is 25 cm. This value is determined based on the average visual acuity of the human population.

Vinegar is primarily composed of acetic acid, which has the chemical formula CH3COOH. This compound is formed from the combination of a methyl group (CH3) and a carboxyl group (COOH). Therefore, the correct answer is CH3COOH.

The general formula of alcohols is R-OH, where R represents an alkyl group. Alcohols are organic compounds that contain a hydroxyl (-OH) functional group bonded to a carbon atom. The alkyl group can vary, resulting in different types of alcohols such as methyl alcohol (CH3OH), ethyl alcohol (C2H5OH), and so on. The general formula helps to represent the structure and composition of alcohols, allowing for easy identification and classification of these compounds.

The correct answer is that work done by a force may be positive, negative, or zero. This is because work is defined as the product of the force applied and the displacement of the object in the direction of the force. If the force and displacement are in the same direction, the work done is positive. If they are in opposite directions, the work done is negative. And if there is no displacement, the work done is zero. Therefore, work can have different values depending on the direction and magnitude of the force and displacement.

A convex lens is thicker at the middle than at the edges because it is designed to converge light rays. The middle part of the lens is more curved, which causes the light rays to bend towards the center. This curvature results in a thicker middle section compared to the edges. This shape allows the lens to focus incoming parallel rays of light to a single point, creating a magnified and focused image.

C2H5OH, also known as ethanol, is the correct answer because it is the chemical formula for the type of alcohol found in wine. Ethanol is produced through the fermentation of sugars by yeast, and it is the main psychoactive ingredient in alcoholic beverages.

The magnification (m) by a thin lens is equal to the ratio of the image height (h') to the object height (h). It can also be expressed as the ratio of the image distance (d') to the object distance (d). This means that the magnification of a thin lens depends on the size and position of the object and the image formed.

The rate of water absorption by the raisins depends on the time they are soaked. Since A removed the raisins after 20 minutes, they had less time to absorb water compared to B who removed them after 2 hours, and C who removed them after 40 minutes. Therefore, the percentage absorption of water for A (PA) would be less than that of B (PB) and greater than that of C (PC). Hence, the correct answer is PA PC.

An esterification reaction is a chemical reaction in which an ester is formed by the reaction between an alcohol and an acid. This reaction involves the condensation of the hydroxyl group (-OH) of the alcohol with the carboxyl group (-COOH) of the acid, resulting in the formation of an ester and water as a byproduct. The correct answer would be the option that describes the formation of an ester through the reaction between an alcohol and an acid.

Museum specimens are preserved in formalin because it is a solution of formaldehyde in water. Formalin acts as a fixative, preventing decay and decomposition of the specimens. It also helps in maintaining the structural integrity of the specimens over a long period of time. Acetone, water, and alcohol are not commonly used for preserving museum specimens as they do not have the same preserving properties as formalin.

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The correct sequence of stages in binary fission in Amoeba is D, C, A, B. In this process, the first stage is D, which involves the elongation of the Amoeba's body. This is followed by stage C, where the nucleus divides into two. Then comes stage A, where the cytoplasm starts to divide, forming two daughter cells. Finally, stage B occurs, where the cell membrane pinches inwards, separating the two daughter cells.

Imbibition of water is the first step for germination of seeds. Imbibition is the process by which seeds absorb water, causing them to swell and become activated. This process softens the seed coat and allows enzymes to be activated, which in turn triggers metabolic processes necessary for germination. Water absorption also helps in the rehydration of the seed tissues, preparing them for further growth. Therefore, imbibition of water is crucial for initiating the germination process in seeds.

The protein body associated with the storage of starch in Spirogyra is called a pyrenoid. Pyrenoids are specialized structures found within chloroplasts that function in the synthesis and accumulation of starch. They are responsible for converting carbon dioxide into starch, which is then stored as a reserve energy source. Leucoplasts and amyloplasts are also involved in starch storage, but they are not specifically associated with protein bodies. Chloroplasts, on the other hand, are responsible for photosynthesis and do not play a direct role in starch storage in Spirogyra.

When the kinetic energy of a body increases by 300%, it means that the body is gaining more energy and moving faster. The linear momentum of an object is directly proportional to its velocity. Therefore, if the body is moving faster (due to the increase in kinetic energy), its linear momentum will also increase. Since the increase in kinetic energy is 300%, the linear momentum will also increase by the same factor, which is 2 times its initial value.