Answer:
A. Because they are compounds, they cannot be pure substances.
Explanation:
The false statement from the given choices is that because they are compounds they cannot be pure substances. In fact, because they are compounds they are pure substances.
Pure substances are made up of elements and compounds and they have the following properties:
- All parts are the same throughout
- Composition is definite
- They cannot easily be separated or broken
- Separation by physical method is not easy
- They have unique sets of physical and chemical properties.
Answer:
the answer is water
Explanation:
During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose.
Weight percentage of nitrogen can be calculated using the following rule:
weight percentage of nitrogen = (weight of nitrogen / weight of urea) x 100
From the periodic table:
molecular mass of carbon = 12 grams
molecular mass of nitrogen = 14 grams
molecular mass of hydrogen = 1 grams
molecular mass of oxygen = 16 grams
therefore:
mass of nitrogen in urea = 2(14) = 28 grams
mass of urea = 12 + 2(14) + 4(1) + 16 = 60 grams
Substitute with the masses in the equation to get the percentage:
weight percentage of nitrogen = (28/60) x 100 = 46.667%
Answer:
Ion-dipole forces
Explanation:
Na⁺ is a cation, that is, an ion with a positive charge.
NH₃ has polar covalent bonds (due to the difference in electronegativity between nitrogen and hydrogen). According to the VESPR theory, it has a trigonal pyramidal shape with a lone pair. As a consequence, it has a net dipole moment and the molecule is polar.
The intermolecular forces between Na⁺ (ion) and NH₃ (dipole) are ion-dipole forces.
Answer:
Promotes Stellar Formation:
-Increased Gravitational Attraction
-Higher Temperature
Does Not Promote Stellar Formation:
-Decreased Gravitational Attraction
-Lower Temperature
Explanation:
Stars need at least three million kelvins to form, and the gravitational attraction helps form the star in the first place.
