The answer is the second choice: variation, overpopulation, adaptation
Well your car <span>insurance</span> should pay for it and nothing els relly unless u report it stolen
Answer:
The correct option is: A carbon atom can complete its valence shell by forming four covalent bonds
Explanation:
Carbon is a chemical element that belongs to the group 14 of the periodic table. The atomic number of carbon atom is 6 and it is denoted by the chemical symbol C.
The electronic configuration of carbon is: 1s², 2s², 2p².
Therefore, there are 2 electrons in the first electronic shell and 4 electrons in the second electronic shell of the carbon atom.
<u>There are </u><u>four valence electrons </u><u>in a carbon atom and thus it can form four covalent bonds to complete its valence shell. Therefore, carbon atom is tetravalent.</u>
Answer:
B
Explanation:
i did this this year in my 9th grade tech class and got it right
Answer:
The correct answer is: Electrical impulses in the heart cause the muscles to contract.
Explanation:
The heart contracts thanks to a series of electrical impulses that travel through the muscles of this organ. The electrical impulse begins in the SA (sinoatrial) node and is transmitted to the muscles that conform the left and the right atria to produce their contraction which will make the atria pump the blood to the ventricles. When the electrical impulse reaches the AV node and then the Bundle of His, this information will transmit to both ventricles and will produce their contraction as well.
The only muscle tissue capable of stimulating their own contractions is the muscle in the heart, the myocardium, thanks to the existence of "pacemaker cells" that are located in the SA node.
The waves in the ECG represent the depolarization of the atria, depolarization of the ventricles, and repolarization of the ventricles.
