Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Name the state class for  iowa admitted to the union december 28, 1846

### Inputs:
table_name: table, columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', 'Date of successors formal installation']

### Response:
SELECT State (class) FROM table WHERE Reason for change = Iowa admitted to the Union December 28, 1846