Science For Grade 9 Trivia
1.
When is an atom considered stable?
Answer:
When it has a full outer valence shell.
Explanation:
When an atom has a full outer orbit or valence shell, it means that all the spaces in the outermost energy level of the atom are filled with electrons. This is a stable configuration for an atom because it satisfies the octet rule, which states that atoms tend to gain, lose, or share electrons in order to achieve a full outer shell. When the outer orbit is full, the atom is less likely to react with other atoms and is considered to be chemically stable.
2.
How many atoms are in Ca(NO3)2?
Answer:
Ca-1 N-2 O-6
Explanation:
The correct answer is Ca-1 N-2 O-6. There is one calcium atom (Ca), two nitrogen atoms (N), and six oxygen atoms (O) in the compound Ca(NO3)2. The subscript numbers indicate the number of each type of atom present in the molecule. The number of nitrogen atoms and oxygen atoms inside the parentheses is multiplied by 2 due to the 2 outside the parentheses.
3.
What does not necessarily indicate a chemical change has occurred?
Answer:
When a smell is produced
Explanation:
The production of smell does not necessarily indicate a chemical change because it can also occur in physical changes. Smells can be produced when substances evaporate or when they are physically broken down, without any chemical reactions taking place. Therefore, the production of smell alone is not sufficient evidence to indicate a chemical change.
4.
What is the equation for photosynthesis?
Answer:
H2O+CO2 (light+chlorophyll) = oxygen+glucose
Explanation:
The equation for photosynthesis is H2O+CO2 (light+chlorophyll) = oxygen+glucose. This equation represents the process by which plants and some other organisms convert carbon dioxide and water into oxygen and glucose, using sunlight and chlorophyll as catalysts.
5.
What is it called when toxins build up in a single organism?
Answer:
Bioaccumulation
Explanation:
Bioaccumulation is the process by which toxins gradually accumulate in the tissues of an individual organism over time. This occurs when the organism is exposed to these toxins through its environment or food sources, and is unable to eliminate them at the same rate they are being absorbed. As a result, the concentration of toxins in the organism's body increases, leading to potential harmful effects on its health.
6.
When can a circumpolar constellation be seen?
Answer:
All year round
Explanation:
A circumpolar constellation can be seen all year round. Circumpolar constellations are located near the celestial pole, either the North or South Pole, and appear to circle around it. As a result, they never dip below the horizon and are visible throughout the year. This is in contrast to other constellations that rise and set with the rotation of the Earth and may not be visible at certain times of the year.
7.
What does an atom become when it gains an electron?
Answer:
Anion
Explanation:
When an atom gains an electron, it becomes an anion. An anion is a negatively charged ion because it now has more electrons than protons. This results in an overall negative charge for the atom. A cation, on the other hand, is a positively charged ion formed when an atom loses an electron. "Onion" is not a term used in chemistry to describe the result of an atom gaining an electron.
8.
Which process describes the change of a substance from a solid state directly to a gaseous state without passing through the liquid state?
Answer:
Sublimation
Explanation:
Sublimation is the process where a substance changes directly from a solid to a gaseous state without passing through the liquid state. This occurs when the molecules of the solid gain enough energy to break free from their fixed positions and enter the gaseous phase. An example of sublimation is dry ice, which is solid carbon dioxide that changes directly into carbon dioxide gas when it warms up.
9.
Which is the largest type of galaxy in the universe?
Answer:
Elliptical galaxy
Explanation:
The largest type of galaxy in the universe is the elliptical galaxy. These galaxies are characterized by their smooth, oval or elliptical shape and typically contain older stars with less interstellar gas and dust, resulting in less active star formation. Elliptical galaxies can vary in size, with some being small and others being massive. They are often found in regions of high galaxy density, such as galaxy clusters, and are one of the main classifications of galaxies based on their shape and structure.
10.
In a circuit, from which end do the electrons flow to the positive end?
Answer:
Negative
Explanation:
In an electrical circuit, electrons flow from the negative end (cathode) to the positive end (anode). This flow is due to the attraction between negatively charged electrons and the positively charged end of the circuit. This movement of electrons constitutes the electric current.
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