50 points! for chemistry. 1.) compare the type of change that occurs when a match is burnt and when a liquid starts boiling. use complete sentences to justify the type of change that occurs. 2.) a glow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion. 3.) read the following passage. the word "atom" was coined by democritus, who, unlike aristotle, believed that matter can be divided only until we get the smallest "indivisible particle." several years later based on macroscopically observable experimental results, dalton proposed that all matter is composed of atoms. many postulates of atomic theory as proposed by dalton were later rejected by jj thompson, who has to his credit the discovery of sub atomic particles like electrons. use information from the passage to justify whether the characteristics of reliable scientific explanations are present in the development of the atomic theory. real answers and explanations only, !

The change during the burning of a match stick is a irreversible chemical change while the change when a liquid starts boiling is reversible chemical change.

A change in which the chemistry of compound change is known as the chemical change.

It can be reversible or irreversible.

Reversible change in the chemical compound when some bonds breaks which don't result in chemical composition of compound overall.

As in case of liquid boiling.

Irreversible chemical change is change in chemical composition which can not be reversed at any rate. As the burning of match stick.

The optimum rate of reaction of the glow reaction is at room temperature.

The optimum temperature is equal to room temperature means the reaction will proceed at fastest rate at room temperature and the reaction will early come to its end.

In contrast, in freezer the reaction will proceed at slow rate. Hence it takes more time to finish the reaction in freezer.

So the glow will remain for longer time in freezer.

Yes, all the scientific theories and their characteristics contributes to the discovery of atom.

As in the start, term was given by Democritus. But he gave the wrong theory about atom. But his term is used now. Aristotle give the right theory about the existence of atom.

Dalton presented many postulates in his atomic theory. In which some were correct but other were proved wrong later.

His correct postulates were also included in JJ Thomson theory of sub atomic particles.

Hence all theories related to an object contributes to its discovery whether it is wrong or right.

according to the u.s. department of agriculture, the label of "certified organic" comes with a set of highly regulated standards for environmental stewardship and resource conservation. some of these include maintenance and improvement of soil quality, prevention of ground and surface water contamination, greenhouse gas regulation, encouragement of biodiversity and conservation of water and energy (see references 1). organic practices integrate natural methods such as mulching, plant diversity, native and adapted plants, crop rotation and the introduction of beneficial insects to control pests without synthetic pesticides.

environmental implications of pesticides

synthetic pesticides ensure high crop yields. while effective in achieving this goal, pesticides contaminate soil, air, ground and surface water, as well as the plants and animals that come into contact with these contaminated sources. freshwater and marine organisms are particularly susceptible to pesticides through agricultural runoff. pesticides also reduce soil fertility (necessitating the use of synthetic fertilizers) and can travel far from the original source, contaminating water and air hundreds of miles from the location of application (see references 2).

health implications of organics

although a subject of particular debate, many recent findings show that organic food is healthier than conventionally grown food. according to the usda, an extensive european union-funded study found that organically grown foods contain more beneficial compounds, such as the vitamins and antioxidants needed to combat many diseases (see references 5). organic milk, meat and eggs are regulated to ensure they are free of hormones administered to conventional livestock and poultry.

health implications of pesticides

pesticides affect human health in three ways: through skin contact, inhalation and ingestion. acute and long-term exposure to pesticides can cause serious health problems for farmers who apply them. the majority of other people are affected by drinking contaminated water and eating contaminated marine life (see references 3). pesticides have been linked to neurological disorders, endocrine and reproductive disorders, immune system deficiencies and cancer. according to the world health organization, acute pesticide poisoning (app) is responsible for significant annual mortality, especially in developing nations (see references 4).

other important considerations

not every small farm or business owner can afford the costly certification process required to be considered "certified organic," even if the farm is not using chemicals. "transitional" farms include those that once used chemicals and are now transitioning to organic-only production. in addition, though organic farming methods offer obvious environmental benefit, an organic apple shipped from around the world creates a different set of environmental problems. locally grown food (particularly locally grown, organic food) is key in sustainable food production.