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Questions in chemistry

[Terjawab] 37) Give reasons why elements of group VIIA in the periodic table are very reactive. 38) Give reason for decreasing reactivity of elements as we go down the group. 39) Give reason why elements of group VA in the periodic table are very reactive. 40) Give reason for increasing reactivity of elements as we go down the group IA. 41) What is the reason for the fact that reactivity of group 'V' element decreases as we go down the group?

[Terjawab] The correct dimensional analysis equation is shown here: [tex]3.00 L CaCl_2 \times \frac{0.100 mol CaCl_2}{1 L} \times \frac{2 mol AgNO_3}{1 mol CaCl_2} \times \frac{1 L}{0.100 mol AgNO_2}[/tex] Did you perform the calculation correctly? A. Yes, I got the correct answer. B. Yes, but I got the wrong answer because of a math error. C. No, I did not set up the calculation correctly.

[Terjawab] Which word equation shows hydrogen reacting with oxygen to form water? A. oxygen + water → hydrogen B. hydrogen + oxygen → water C. oxygen + water → hydrogen + water D. hydrogen + water → oxygen

[Terjawab] Which reaction shows that the enthalpy of formation of $H _2 S$ is $\Delta H_{ f }=-20.6 kJ / mol$? A. $H _2(g)+ S ( s )+20.6 kJ \rightarrow H _2 S$ B. $H _2(g)+ S ( s ) \rightarrow H _2 S+20.6 kJ$ C. $2 H (g)+ S (s)+20.6 kJ \rightarrow H _2 S$ D. $H _2(g)+ S ( s ) \rightarrow H _2 S-20.6 kJ$

[Terjawab] What is the correct electron configuration of phosphorus $(P)$? A. $1 s^2 2 s^2 2 p^6 3 s^2 3 p^3$ B. $1 s^2 2 s^2 2 p^3 3 s^2 3 p^3$ C. $1 s^2 2 s^2 2 p^6 2 d^5$ D. $1 s^2 2 s^2 2 p^6 3 s^1 3 p^4$

[Terjawab] The chemical equation for the formation of ammonia is unbalanced. [tex]3 H_2(g)+N_2(g) \rightarrow NH_3(g)[/tex] If three molecules of hydrogen react with one molecule of nitrogen, how many molecules of ammonia would be formed? A. 1 B. 2 C. 3 D. 4

[Terjawab] According to the Arrhenius definitions of acids and bases, choose the acids from the list of acids and bases. Check all that apply. HBr [tex]$Sr ( OH )_2$[/tex] HClO [tex]$H _2 S$[/tex] LiOH

[Terjawab] A laboratory technician combined sodium hydroxide with excess iron(II) nitrate. A reaction took place according to this chemical equation: $2 NaOH + Fe ( NO _3)_2 \rightarrow NaNO _3+ Fe ( OH )_2$. The reaction produced 3.70 grams of iron(II) hydroxide. Assuming the reaction came to completion, what was the initial mass of sodium hydroxide? A. 1.6 g B. 2.0 g C. 3.3 g

[Terjawab] Which balances the equation [tex]Mg + O _2 \rightarrow MgO[/tex]? A. [tex]Mg +2 O _2 \rightarrow 4 MgO[/tex] B. [tex]2 Mg +2 O _2 \rightarrow 2 MgO[/tex] C. [tex]2 Mg + O _2 \rightarrow 2 MgO[/tex] D. [tex]2 Mg +2 O _2 \rightarrow 4 MgO[/tex]

[Terjawab] "K" is the chemical symbol for which of the following substances? A. Iron B. Barium C. Calcium D. Potassium