Answer:
- <em>The substance that cannot be broken down by a chemical change is </em><u>tungsten (option C)</u>
Explanation:
Chemical compounds are pure <em>substances</em> constituted by two or more different elements. They have fixed composition and have their unique chemical properties, different from their individual components (elements) and from other compounds.
Thus chemical compounds can<em> be broken down by a chemical change</em> into their individual atoms or other simpler compounds.
The substances indicated by the choices <em>A) methane, B) propanal, and D) water</em>, are chemical compounds with chemical formulae CH₄, C₃H₆O, and H₂O, respectively, so they<em> can be broken down into their consitutents by a chemical change</em>.
On the other hand, <em>tungsten</em> is one of the 118 known elements. Its atomic number is 74, and its chemical symbol is W.
Then, being tungsten an element, which means that all the atoms present in a pure sample have the same number of protons and electrons, it <em>cannot be broken down by a chemical change</em>. The only way to split an atom of tungsten is by a nuclear reaction.
Answer:
1.08 grams of nitrogen
Explanation:
Thermally ammonium perchlorate dissociate as shown in figure.
Thus as per equation two moles of ammonium perchlorate will give four moles of water, two moles of oxygen, one mole of chlorine and one mole of nitrogen,
The molar mass of ammonium perchlorate = 117.5g/mol
Two moles of ammonium perchlorate = 2X 117.5 = 234 g
The molar mass of nitrogen = 28g
thus 234 grams of ammonium perchlorate will give 28 grams of nitrogen
Hence 9 grams of ammonium perchlorate will give 1.08 grams of nitrogen
"People should remove native plants around watersheds" option should a person avoid doing in order to better protect the quality of watersheds.
<u>Option: A</u>
<u>Explanation:</u>
Watershed is basically a source of large amount of water like river, sea, etc to another location like lake, ponds and stream.This is seen majorly during rainy season by water harvesting to supply further for farming, portable water plant, manufacturing sectors, enrich habitat to number of plants and animals, etc. Waterways face issues when erosion, pollutants and runoff of animal waste take place, which act as barrier for water flow, as it decreases the quality which affect aquatic animals life, reduce oxygen content. Native plants near watersheds is also a habitat for many animals and species thus it should not be removed until some major flaw occurs.
Answer:Nothing, the photon just bounces off the surface.
Explanation:
According to Albert Einstein, a photoelectron can only be emitted from a metal surface when the energy of the incident photon is greater than the work function of the metal.
In the scenario described in the question, the work function of the metal is greater than the energy of the photon. Hence, the photon just bounces off the metal surface without emitting any electron.
Answer: 3.97 moles HCl
Explanation: Solution:
2.39x10²⁴ atoms HCl x 1 mole HCl /
6.022x10²³ atoms HCl
= 3.97 moles HCl
