【简答题】某研究小组对用H 2 O 2 分解生成H 2 O和O 2 的实验条件进行探究.他们进行了以下实验: ①往盛有5mL 5% H 2 O 2 溶液的试管中,伸入带火星的木条,木条不复燃. ②往盛有5mL w% H 2 O 2 溶液的试管中,加入a g MnO 2 ,伸入带火星的木条,木条复燃. ③往盛有5mL w% H 2 O 2 溶液的试管中,加入a g Fe 2 O 3 ,伸入带火星的木条,木条复...
【简答题】某研究小组对用H 2 O 2 分解生成H 2 O和O 2 的实验条件进行探究.他们进行了以下实验: ①往盛有5mL 5% H 2 O 2 溶液的试管中,伸入带火星的木条,木条不复燃. ②往盛有5mL w% H 2 O 2 溶液的试管中,加入a g MnO 2 ,伸入带火星的木条,木条复燃. ③往盛有5mL w% H 2 O 2 溶液的试管中,加入a g Fe 2 O 3 ,伸入带火星的木条,木条复...
【单选题】Which one of the following statements about an imprest system of petty cash is correct?
A.
An imprest system for petty cash controls small cash expenditures because a fixed amount is paid into petty cash at the beginning of each period,
B.
The imprest system provides a control over petty cash spending because the amount of cash held in petty cash at any time must be equal to the value of the petty cash vouchers for the period.
C.
An imprest system for petty cash can operate without the need for petty cash vouchers or receipts for spending.
D.
An imprest system for petty cash helps with management of small cash expenditures and reduces the risk of fraud.