![]() Typically, methylation turns genes “off” and demethylation turns genes “on.” Histone modificationĭNA wraps around proteins called histones. This chemical group can be removed through a process called demethylation. Typically, this group is added to specific places on the DNA, where it blocks the proteins that attach to DNA to “read” the gene. Oxygen layer protects us from harmful radiations of the sun.DNA methylation works by adding a chemical group to DNA. Shape and size are the physical properties of a substance. Answerīurning of paper is chemical change. AnswerĮvolution of a gas may occur in a chemical change. AnswerĬhanges in which new substances are formed are called chemical changes. The chemical name of baking soda is sodium hydrogen carbonate. The mass of a substance changes during a chemical change. Answerīurning of cracker is a physical change. AnswerĬooking of rice is a physical change. The process of photosynthesis is a chemical change. In chemical changes, new substances are produced. AnswerĪ chemical change is also called a chemical reaction. AnswerĬhanges are broadly classified as physical and chemical changes. We must use concentrated sulphuric acid for crystallisation of copper sulphate. Stretching of rubber band is a physical change. Answerīurning of any substance is a chemical change. Stainless steel is made by mixing aluminium with carbon. properties of a substance change are called physical changes. ![]() Two methods by which rusting of iron can be prevented are …………………. AnswerĬarbon dioxide turns lime water, milky due to the formation of …………………. AnswerĬutting a log of wood into pieces is a …………………. Large crystals of pure substances are obtained by _. Answerīurning of candle shows both _ and _ changes. ![]() The formula of sodium hydrogen carbonate is _. Rusting can be prevented by _, _ and _ the iron articles. Answerįor rusting, the presence of both _ and _ is important. Magnesium hydroxide is produced by mixing _ with _. AnswerĬalcium carbonate is decomposed to form _ and _. No new substance is formed in a _ change. Physical properties of a substance consists of_, _, _ and state. Answerīroadly, changes are of two types, _ and _. Which property stays the same during physical and chemical changes? Which of the following is not a clue that could indicate the occurrence of a chemical change? Which characteristic best describes a physical change? (d) neither physical nor chemical change Answer If the chemical properties of a substance remain unchanged and its appearance or shape changes, it is called a When a new substance is formed with different properties than those of the original substance, it is called a (d) Neither physical nor chemical change Answer Which of the following changes can easily be reversed? AnswerĪnswer: (c) A plant collecting sunlight and turning it into food. (c) A plant collecting sunlight and turning it into food. (b) Taking a glass of water and freezing it by placing it in the freezer. Which of the following is an example of a chemical change? AnswerĪnswer: (b) Falling of a glass cup from the counter and its shattering on the ground. (d) Baking a birthday cake for your mother. (c) Lighting a piece of paper on fire causing it to bum up and leave ashes. (b) Falling of a glass cup from the counter and its shattering on the ground. (a) Mixing of baking soda and vinegar together to cause bubbles and foam. Which of the following is an example of a physical change? Which of the following is a chemical change?Ī change of state from one form to another is a (c) Cutting a log of wood in small piecesĪnswer: (c) Cutting a log of wood in small pieces Which among the following is a physical change? (b) chemical and physical changes respectively. (a) physical and chemical changes respectively. On cooling, beautiful blue-coloured crystals got separated (step II). Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). The process of depositing a layer of zinc over iron is known as When carbon dioxide is passed through lime water, the substance formed is Properties like size, shape, colour, state of a substance areĭuring a physical change, a substance undergoes a change in its Answer: (a) Heat may be given out but never absorbed
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