Answer: pure substances.
Explanation:
The given substances are:
All what surrounds us, which has mass and occupies spaces, is matter. There are two kind of matter: pure substances and mixtures.
Pure substances have a uniform and constant composition. On the other hand, mixtures are combinations of two or more pure substances in any arbitratry ratio.
Pure substances may be elements or compounds. The elements are the substances conmposed by one only kind of atom. In the list of substances given, Li and O₂ are elements: all the atoms in Li are lithium, and all the atoms in O₂ are oxygen atoms.
Compounds are the chemical combination of two or more different kind of atoms. In the given list H₂O₂ and NaCl are compounds. As you see, H₂O₂ contains atoms of hydrogen and oxygen, chemically bonded, in a fixed ratio (2 atoms of hydrogen by 2 atoms of oxygen). And NaCl has atoms of Na (sodium) and Cl (chlorine), chemicaly bonded, in a fixed ratio (1:1).
There are only 118 known elements and you can find them in any modern periodic table. Therer are virtually infinitely many compounds since many different combinations of the elements can be attained.
Elements and compounds have in common that they are classified as pure substances.
Answer:
6.022×1023 particles are present in one mole of a substance while about 7.5 x 1018 grains of sand are present on earth's beaches.
Explanation:
Mole is used in chemistry for the calculation of mass of an atom. 6.022×1023 particles are present in one mole of a substance while about 7.5 x 1018 grains of sand are present on earth's beaches. According to this data which shows that the size of mole is greater than the number of sand grains present on Earth’s beaches because there are higher particles are present in mole as compared to sand grains. So the mole has big size.
Answer:
The dots were not properly located and arrows are not used in Lewis structures
Explanation:
If we intend to write a Lewis structure for a compound, that lewis structure must consist of only dots. These dots actually show the valence electrons on the outermost shell of the molecule.
We do not involve arrows when writing dot electron structures for compounds. The valence electrons of magnesium ought not to be written together because they are not a lone pair, rather they are two unpaired electrons. The use of an arrow suggests a coordinate covalent bond which is not the case here.
The correct lewis structure for MgCl2 is shown in the image attached to this answer.
Answer:
Oil and vinegar separate because it is a suspension
Explanation:
When you let suspensions sit the particles begin to layer out, in the salad dressing the oil layers out on top of the vinegar. The two layers of oil and vinegar don't actually dissolve in each other. The layer with the lower density (oil) floats on top of the layer with a higher density (vinegar)
