Answer:
(1) It shows arrangement of elements based on modern periodic law.
(2) There are 18 vertical columns known as groups.
(3) There are 7 horizontal rows known as periods.
Answer:
Monsoon seasonal diseases can be avoided by keeping surroundings clean, removing stagnant water, eating homemade food, washing hands properly, eating clean and drinking boiled water.
Explanation:
1. Make efforts in making the environment mosquito free by proper cleaning and removing stagnant water as well.
2. Use mosquito repellant, mainly net that has no side effects and is ecofriendly.
3. Avoid moving to crowded places to prevent viral infections.
4. Consume food made at home and boiled water.
5. Wash hands before consuming food.
Answer:
18.
Explanation:
1) according to the reaction (M(Fe)=56; M(O₂)=32; V₀=22.4):
4Fe+3O₂⇒2Fe₂O₃; - ν(O₂)=0.75*ν(Fe);
2) ν(Fe)=m(Fe)/M(Fe)=60/56≈1.071 [mol];
3) ν(O₂)=0.75*1.071=0.804 [mol];
4) V(O₂)=V₀*ν(O₂); ⇒ V(O₂)=22.4*0.804=18 [lit].
Answer:
the answer is d hope this helps
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Explanation:
Answer:
4. H-3 and He-4
Explanation:
H-3 means hydrogen with a mass number of 3. Mass number is the addition of protons and neutrons in the nucleus. Hydrogen always has 1 proton because it has atomic number 1, therefore the number of neutrons is found by subtracting 1 from the mass number (3).
3-1= 2 neutrons
He-4 also has 2 neutrons. He-4 has mass number 4, which means that its protons and neutrons added together equals 4. Helium has 2 protons because it has atomic number 2.
Therefore 2 + neutrons =4
neutrons =4-2
neutrons =2
