Found in yogurt, sour milk, and produced in muscles during exercise, lactic acid has the chemical formula C3H6O3.  What is the mass % of oxygen in this molecule?

Which of the following is/are considered to be a weak electrolyte? CH3COOH (aq)  NaNO3 (aq) C6H12O6 (aq) HBr (aq) NaCl (s)  

Consider the following reactions:   2Mg(s) + O2​(g) ⟶ 2MgO(s)  2KClO3​(s)⟶ 2KCl(s) + 3O2​(g)  CH4​(g) + 2O2​(g) ⟶ CO2​(g) + 2H2​O(g)  HCl(aq) + NaOH(aq) ⟶ NaCl(aq) + H2​O(l)  AgNO3​(aq) + NaCl(aq) ⟶ AgCl(s) + NaNO3​(aq)  CaO(s) + H2O(l) ⟶ Ca(OH)2 (aq) Which reaction(s) is/are double displacement – precipitation reactions?

Which of the following name–formula pairs is incorrect?

A coffee-fueled study group consumes a total of 388 g of caffeine (C8H10N4O2). How many moles (in mol) of caffeine they have consumed? Hint: molar mass of C8H10N4O2 is 194.22 g/mol

Tums® tablets contain calcium carbonate (CaCO3), which neutralizes stomach acid (HCl). The balanced reaction is:  CaCO3 (s)  +  2 HCl (aq)  ⟶   CaCl2 (aq)  +  H2O(l)  +  CO2 (g) If a patient has 0.200 mol of stomach acid (HCl) to neutralize, and enough Tums were taken to completely neutralize it, how many grams of CO2 gas are released? Hint: molar mass of CO2 is 44.01 g/mol

Suppose that after performing the Permuted Choice One (PC-1) defined in Table C.3(a), you obtain the following 56-bit (8 rows and 7 columns) binary string, which is divided into two 28-bit substrings: C0 and D0. Question8_1.jpg You then perform the left shift the first 28 bits C0 (rows 1-4) and next 28 bits D0 (rows 5-8) based on Table C.3(d). For the first round of DES, both C0 and D0 just rotate to the left one round. You get the following 56-bit binary string:                                               0 0 0 1 1 1 1                             0 0 1 1 0 0 1                     1 0 1 0 1 0 1                     0 1 1 1 1 1 0                     1 0 1 0 1 0 1                     0 0 1 1 0 0 1                     1 0 0 0 0 1 1                     1 1 1 1 1 1 0 Perform Permuted Choice Two (PC-2) to reduce the 56-bit binary string into 48-bit binary string (organized into a matrix of 6 by 8). This is the first subkey K1.

Why is it not practical to use an arbitrary reversible substitution cipher of the kind shown in the following table ( Table 4.1 in the textbook)? Question2.jpg

In DES, the first step of driving subkey is to perform the Permuted Choice One (PC-1) defined in Table C.3(a). For the following 64-bit key, perform the PC-1 to reduce it from 64 bits to 56 bits.       1 1 1 1 1 1 1 0       1 1 0 1 1 1 0 0       1 0 1 1 1 0 1 0       1 0 0 1 1 0 0 0       0 1 1 1 0 1 1 0       0 1 0 1 0 1 0 0       0 0 1 1 0 0 1 0       0 0 0 1 0 0 0 0

What is a meet-in-the-middle attack?