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Alisiya [41]
2 years ago
9

Why do we observe national day​

Chemistry
1 answer:
WITCHER [35]2 years ago
5 0

A national day is a day on which celebrations mark the nationhood of a nation or state. It may be the date of independence, of becoming a republic, or a significant date for a patron saint or a ruler (such as a birthday, accession, or removal). The national day is often a public holiday.

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Curium – 245 is an alpha emitter. Write the equation for the nuclear reaction and identify the product nucleus.
BabaBlast [244]

Answer:

Please find the complete solution in the attached file.

Explanation:

7 0
3 years ago
Type the correct answer in the box. Express your answer to two significant figures. An industrial vat contains 650 grams of soli
SashulF [63]

88.98 %

The Balance Chemical Equation is as follow,

                                  2 HCl + Pb(NO₃)₂     →    2 HNO₃ + PbCl₂

According to equation,

          331.2 g (1 mole) Pb(NO₃)₂ produces  =  278.1 g (1 mole) PbCl₂

So,

                 870 g of Pb(NO₃)₂ will produce  =  X g of PbCl₂

Solving for X,

                     X  =  (870 g × 278.1 g) ÷ 331.2 g

                     X  =  730.5 g of PbCl₂

Therefore,

               Theoretical Yield =  730.5 g

Also as given,

                Actual Yield =  650 g

So using following formula for percentage yield,

                        %age Yield  =  (Actual Yield / Theoretical Yield) × 100

Putting values,

                        %age Yield  =  (650 g / 730.5 g) × 100

                        %age Yield  =  88.98 %

Brianliest please and thank you.

4 0
3 years ago
Which statement BEST describes elements that would create the MOST polar bonds?
Umnica [9.8K]
C) elements from the top left and the top right of the periodic table
5 0
3 years ago
Read 2 more answers
Determine the pH of 0.050 M HCN solution. HCN is a weak acid with a Ka equal to 4.9 x 10-10<br> DONE
nadezda [96]

Answer:

The pH of the solution is 5.31.

Explanation:

Let "\alpha is the dissociation of weak acid - HCN.

The dissociation reaction of HCN is as follows.

                  HCN+H_{2}O\rightarrow H_{3}O^{+}+CN^{-}

Initial                  C                         0            0

Equilibrium        c(1- \alpha)              c\alpha c\alpha

Dissociation constant = Ka= c\alpha \times \frac{c\alpha}{c(1-\alpha)}

=\frac{c\alpha^{2}}{(1-\alpha)}

In this case weak acids \alpha is very small so, (1-\alpha ) is taken as 1.

Ka=C\alpha^{2}

\alpha=\sqrt\frac{ka}{c}

From the given the concentration = 0.050 M

Substitute the given value.

\alpha=\sqrt\frac{4.9\times 10^{-10}}{0.05}=9.8\times 10^{-4}

[H_{3}O^{+}]=c\alpha

[H_{3}O^{+}]=0.05\times 9.8\times 10^{-4}= 4.9\times10^{-6}

pH= -log[H_{3}O^{+}]

=-log[4.9\times10^{-6}]

=6-log 4.9= 5.31

Therefore, The pH of the solution is 5.31.

7 0
3 years ago
Read 2 more answers
Почему молекулы алканов в пространстве имеют зигзагообразную форму
Solnce55 [7]

Answer:

Alkanes (also saturated hydrocarbons , paraffins ) are acyclic hydrocarbons of a linear or branched structure, containing only simple bonds and forming a homological series with the general formula C n H 2n + 2 .

Explanation:

ll alkanes belong to a larger class of aliphatic hydrocarbons. Alkanes are saturated hydrocarbons, that is, they contain the maximum possible number of hydrogen atoms for a given number of carbon atoms. Each carbon atom in the alkane molecules is in a state of sp 3 - hybridization  - all 4 hybrid orbitals of the C atom are identical in shape and energy, 4 bonds are directed to the vertices of the tetrahedron at angles of 109 ° 28 '. C – C bonds are σ bonds characterized by low polarity and polarizability . The C – C bond length is 0.154 nm , the C – H bond length is 0.1087 nm.

The simplest member of the class is methane (CH 4 ). The hydrocarbon with the longest chain — noncontactrictan C 390 H 782 — was synthesized in 1985 by English chemists I. Bidd and MK K. Whiting

6 0
3 years ago
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