Chemistry

Which statement describes a chemical change? When a piece of glass is heated, it melts. When a lump of coal is burned, it releases heat. When a teaspoon of table salt is added to water, it dissolves. When a lump of silver is hammered, it flattens into a thin sheet.

A student is examining two samples of the element lead. Which statement best describes the two samples? Both the physical and chemical properties are the same in each sample. Both the physical and chemical properties of the lead change from sample to sample. The physical properties of the lead are the same in each sample. The chemical properties of the lead change from sample to sample.

Which evidence is the best example of a chemical change? boiling condensing dissolving rusting

Average Atomic Mass Cakulate the average atomic mass of the following imaginary elements based on the information supplied. % occurrence isotope mass 1. Zb-318 34.71 317.999785 Zb-32 o 43.61 319.989061 Zb-322 21.68 322000088 2. Omg -420 20.05 419.979962 Omg-424 39.21 424.001321 Omg -425 40.74 424998356 3. Sa-291 20.01 291.020389 Sa-293 28.71 292.987681 Sa-295 51.28 295.011006 4. Bg-400 29.21 399.979962 Bg-404 40.05 404.001321 Bg-406 30.74 405.998356 5. Lp-372 51.28 372.000809

In lab, you are asked to measure out 30mu L of buffer solution. Which item below would be the most appropriate container for this very small volume? test tube microcentrifuge tube beaker Erlenmeyer flask with stopper

6.80 The following electron configurations represent excited states. Identify the element and write its ground-state condensed electron configuration. 1s^22s^22p^43s^1 b. [Ar]4s^13d^104p^25p^1 [Kr]5s^24d^25p^1

Infer which of the following is an example of a chemical change? A. water evaporating B. ice cream melting C. carbon joining with oxygen to form carbon dioxide D. a pencil breaking

What are the products of the combustion of a hydrocarbon? carbon dioxide and water carbon and hydrogen carbon dioxide and hydrogen

How are elements with similar properties found on the periodic table? by atomic number by periods by atomic mass by groups

Question #2 When electric current passes through water, the water undergoes a chemical change and decomposes into oxygen gas and hydrogen gas. water chemical chango hydrogen gas + oxygen gas Select the correct choice from the drop-down to correctly complete the following statement. The total mass of hydrogen gas and oxygen gas will be square the mass of the water.