a chemical change occurs when a piece of wood \_\_\_\_...
a chemical change occurs when a piece of wood \_\_\_\_.a. is splitb. is paintedc. decaysd. is cut
we’re being asked which of the following conditions occurs when a chemical change happens to a piece of wood let’s first define a physical change and a chemical change.physical change → there is a change in a matter as it goes from one physical state to another.chemical change → atoms rearrange themselves to create a new substance. now, let’s take a look at each condition:[readmore]a. is splitsplitting wood is only reducing its size. physical changeb. is paintedpainting wood is only placing paint on top of it and not really affecting the composition of the wood.  physical changec. decaysdecaying changes the integrity of the wood itself and transforms it into things like soil. chemical changed. is cutcutting wood is only reducing its size. physical changea chemical change occurs when a piece of wood c. decays.
hi,
all physical changes are not
reversible cutting of tree is an irreversible physical change
all chemical changes are not
necessarily irreversible

the reaction between hydrogen and oxygen to form water is an
example reversible chemical reaction the reaction can be
represented as:
h2 + 1/2 o2→ h2o when the water on the surface of the ocean rises and falls alternately, they are called waves. during a storm, the winds blowing at very high speed form huge waves. these may cause tremendous destruction. when a volleyball player smashes a ball, he changes the speed as well as direction of the ball. this is a change of state of motion. however, a change in state of motion is said to occur also when either of the two changes individually. recycling is nothing but rehabilitating the use of old and used items by redoing. e.g., plastics. melt again and cast and reuse.
similary waste and thrown of materials such as tins and cans also can be recycled by reproducing useful materials from them.
drain water is treated and recycled for use. oil from drains of industries are stored and reclailmed and used after mixing up chemcials to get back the qualities required.
in all the cases, either for lesser important uses or for the same use itself can be had, depending upon the qualilty of recycled product. thus waste othewise thrown out can be recycled, by duly segregating them for a particular recycling use, known as waste management. e.g. plastics. papers, steel and ferrous items. non-ferrous metals, acids, rubber etc. segregated for recycling.
vr different cells in the body have different instructions or marching orders as to how they are to grow and function. sometimes clumps of cells with diverse marching orders form a tumor and mature into very different types of tissue. one type is called a dermoid cyst. these can contain a variety of different tissues including hair. see more... The physical and chemical properties of elements depend on the number of valence electrons. Elements present in the same group have the same number of valence electrons. Therefore, elements present in the same group have similar physical and chemical properties. pure substances are made up of same type of particles or atoms. all the elements and compounds are pure substances because they contain the same kinds of particles. examples: hydrogen, carbon dioxide childhood is a time of tremendous brain development. the young brain literally changes shape and size in response to everything encountered from new environment, to life experiences, to caretakers and to relationships. hint: at first think about the structure of ester so that you are able to draw the structure for a given molecular formula. the structure of ester is $r - co - o - r'$.complete answer:an ester is a chemical compound derived from an acid in which at least one –oh group is replaced by an $ - o - $ alkyl group. esters are generally derived from substitution reactions of a carboxylic acid and an alcohol which is also known as an esterification reaction. from the given molecular formula we can draw only two structures of esters. they are ethyl formate and methyl acetate. their structures are $h - co - o - c{h\_2} - c{h\_3}$ and $c{h\_3} - co - o - c{h\_3}$.additional information:esterification is the process of combining carboxylic acid and alcohol to give at least one ester and water.$r - co - oh + r - oh \rightleftharpoons r - co - o - r' + {h\_2}o$in the above reaction, the forward reaction gives us esterification and the backward reaction gives us hydrolysis of the ester. the hydrolysis of esters in the presence of alkalis such as potassium hydroxide (lye) or sodium, a reaction called saponification which is utilized in the preparation of soaps from fats and oils and is also used for the quantitative estimation of esters.note:esters are common in organic chemistry and biological materials, and often have a pleasant characteristic, fruity odor. this leads to their extensive use in the fragrance and flavor industry. ester bonds are also found in many polymers. **Pure substance – ethyl alcohol, oxygen, carbon, distilled water mixture – blood, steel**