Answer:
A
Explanation:
B) pollution doesn't affect water
C) Air pollution makes carbon dioxide
D) air pollution does not affect temperature
Answer: He should add a single dot below the symbol to correct the electron dot diagram of an aluminium atom.
Explanation: Electron dot structures are the structures in which valence electrons around an atom are shown. The electrons are represented as dots in these structures.
Aluminium is the 13th element of the periodic table.
Electronic configuration of Aluminium is given by:
Valence electrons of aluminium = 3
In the given image, 2 valence electrons are shown and total number of valence electrons are 3. So, in order to correct the diagram, he should add a single electron below the symbol.
Answer:
D
Explanation:
Na+ and Cl- cancel each other out leaving only option D as the correct answer.
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Number of mole : mass/ molar mass
87g/ (2 x 16) = 2.719 mol
volume = number of mole x molar volume
volume = 2.719 x 22.4
volume = 60.906 L
Answer: Most of the hormones released by endocrine system are regulated by negative feedback mechanism.
- Negative feedback mechanism functions to reduce the intensity of original stimulus in order to maintain homeostasis.
Explanation:
When blood calcium levels are decreased, parathyroid gland releases parathyroid hormone (PTH).
PTH acts on bone and stimulate bone resorption by promoting osteoclastic activity. It stimulates reabsorption of calcium in kidneys. PTH promotes calcitriol synthesis that acts on small intestine to increase calcium absorption.
Action of PTH increases blood calcium levels.
When blood calcium levels are increased, thyroid gland releases hormone calcitonin.
Calcitonin opposes PTH and acts to deposit calcium in the bone.
Calcitonin acts on osteoblasts and promote increase in bone mass.
Action of calcitonin decreases blood calcium levels.