Answer:
True
Explanation:
The nitrogen fixation is a process that involves conversion of atmospheric nitrogen to nitrates in the soil. This process is mainly performed by nitrogen-fixing bacteria present in the soil.
The nitrogen fixation is important for plants and animals. The nitrogen present in the atmosphere cannot be used directly by animals and plants. The nitrogen is main constituent of chlorophyll that is required for the process of photosynthesis and for amino acids that synthesize proteins. Thus, Nitrogen fixation makes nitrogen gas useful to crops.
Northern lights or auroras can be seen within the ionosphere sub-layer.
Their atoms have the same atomic mass.
Their atoms have the same number of protons and electrons.
Their atoms have the same number of neutrons.
Answer: Option A
Explanation:
The elements are arranged in a periodic table based on their properties. The group of similar elements share common characteristics and hence kept in the same periods.
The elements having same number of valence electrons in their outer shell. As they have same number of valence electrons they have similar properties in terms of reactivity, stability, et cetera.
Hence, the correct answers is option A
All elements in a column in the periodic table, their atoms have the same number of valence electrons. (Option A)
In the periodic table, elements are organized into columns called groups or families.
Elements within the same group have similar chemical properties because they have the same number of valence electrons.
Valence electrons are the electrons in the outermost energy level of an atom, and they play a crucial role in determining an element's chemical reactivity and bonding behavior.
While elements in the same group have similarities in terms of valenceelectrons, they may have different numbers of protons and electrons (giving them different atomic numbers and overall electrical charge) and different numbers of neutrons (giving them different isotopes with varying atomic masses).
Learn more about valence electrons here: brainly.com/question/28896521
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B. stigma
C. anther
D. filament
Answer: Stem cell research has the potential to treat diseases that are currently burdened with high health care costs—especially chronic conditions such as heart disease, Alzheimer's disease or diabetes, the costs of which threaten to cripple the healthcare system.
c. stays the same
b. decreases
d. both b and c
Answer:
Option C, stays the same
Explanation:
Heat flow by vibrating the molecules in any medium. Therefore, some medium is essential for heat transfer and hence no heat flows across an insulated vacuum can. Without any medium, heat transfer is stopped which means that neither the heat from outside environment can flow into the can nor it can flow from the can into the external environment.
Hence, the heat contained within the can shall remain the same.
Thus, option C is correct
The discoverers of DNA were not James D Watson and Francis Crick. They are the first scientist to formulate an accurate description of the DNA’s (deoxyribonucleic acid) complex , double-helical structure. They discovered that base pairing nucleotides must be; adenine and thymine; and cytosine and guanine. These base pairs are held together by a hydrogen bond, atype of chemical reaction that s easy to break and easy to reform. The statement is “DNA is a double helix made of two strands linked together with hydrogen bonds.”